Prospectus
--------------------------------------------------------------------------------
6,000,000 Shares

                                                      Registration No. 333-33436
                                                               Filed pursuant to
                                                           Rule 424(b)(2) of the
                                                          Securities Act of 1933
CYTOGEN CORPORATION

Common Stock


Cytogen  Corporation  hereby offers  1,820,000 shares of its common stock to the
State of Wisconsin  Investment  Board.  Such  issuance,  together with its prior
issuances  hereunder of 2,000,000 shares of common stock to Advanced  Magnetics,
Inc. and 2,179,158  shares of common stock to Acqua  Wellington  North  American
Equities Fund, Ltd. constitute 5,999,158 of the 6,000,000 shares of common stock
that may be issued by the Company  hereby.  The  remaining  842 shares of Common
Stock may be issued at prices and on terms to be determined at the time of sale,
and  we  will  provide  a  prospectus  supplement  that  will  contain  specific
information about the terms of any such sale. The prospectus supplement may also
add, update or change information contained in this prospectus.

We may sell  common  stock  to or  through  underwriters  or  directly  to other
purchasers  or  through  agents  as  set  forth  in  the  applicable  prospectus
supplement.  Certain terms of the offering and sale of common stock,  including,
where  applicable,  the  names  of any  underwriters,  dealers  or  agents,  any
applicable commissions,  discounts and other items constituting  compensation of
underwriters, dealers or agents, and the proceeds to Cytogen from the sale, will
be set forth in a prospectus supplement.

Our  common  stock is listed on the  Nasdaq  National  Market  under the  symbol
"CYTO."

BEFORE  BUYING ANY SHARES YOU SHOULD READ THE  DISCUSSION  OF MATERIAL  RISKS OF
INVESTING IN OUR COMMON STOCK UNDER "RISK FACTORS" BEGINNING ON PAGE 4.

NEITHER  THE  SECURITIES  AND  EXCHANGE  COMMISSION  NOR  ANY  STATE  SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS
PROSPECTUS  IS TRUTHFUL OR  COMPLETE.  ANY  REPRESENTATION  TO THE CONTRARY IS A
CRIMINAL OFFENSE.

                  The date of this prospectus is June 19, 2001.






You should rely only on the  information  contained in this  prospectus  or in a
prospectus supplement or amendment. We have not authorized anyone to provide you
with different information.  We may offer to sell, and seek offers to buy shares
of Cytogen Corporation common stock only in jurisdictions where offers and sales
are  permitted.  The  information  contained in this  prospectus or a prospectus
supplement or amendment or incorporated  herein by reference is accurate only as
of the date on the front of the document.

TABLE OF CONTENTS
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Cytogen Corporation......................   3
Risk factors.............................   4
Forward-looking statements...............  16
Use of proceeds..........................  17
Plan of Distribution.....................  18
Legal matters............................  19
Experts..................................  19
Where you can find more information......  19
Information incorporated by reference....  20
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Cytogen(R), ProstaScint(R), OncoScint(R), Quadramet(R), IFP Database(TM) and the
Cytogen  and  AxCell  Biosciences  Corporation  logos are our  marks.  All other
trademarks,  servicemarks  or trade names referred to in this prospectus are the
property of their respective owners.

Our  principal  executive  offices are located at 600 College Road East CN 5308,
Princeton, New Jersey 08540-5308 and our telephone number is (609) 750-8200. Our
web site is http://www.cytogen.com. The information found in our web site is not
part of this prospectus.

                                       2




CYTOGEN CORPORATION

Cytogen is an established  biopharmaceutical company with two principal lines of
business,  proteomics and oncology. We are extending our expertise in antibodies
and  molecular   recognition   to  the   development   of  new  products  and  a
proteomics-driven  drug discovery  platform.  We have  established a pipeline of
product  candidates  based upon our proprietary  antibody and prostate  specific
membrane antigen,  or PSMA,  technologies.  We are also developing a proprietary
protein  pathway  database  as a drug  discovery  and  development  tool for the
pharmaceutical and biotechnology industries.

Our cancer management franchise currently comprises three marketed  FDA-approved
products:  ProstaScint,  used to image the extent and spread of prostate cancer;
OncoScint  CR/OV,  marketed as a diagnostic  imaging  agent for  colorectal  and
ovarian cancer and  Quadramet,  marketed for the relief of  cancer-related  bone
pain.  We are  extending  our  cancer  pipeline  by  exploiting  PSMA,  which we
exclusively  licensed from Memorial  Sloan-Kettering  Cancer  Center.  PSMA is a
unique   antigen  highly   expressed  in  prostate   cancer  cells  and  in  the
neovasculature of a variety of other solid tumors,  including  breast,  lung and
colon. We are developing our PSMA technology as part of our approach to offering
a full range of prostate cancer management  products and services throughout the
progression  of  the  disease,   including  gene-based  immunotherapy  vaccines,
antibody-delivered  therapeutic  compounds  and novel  assays for  detection  of
primary  prostate cancer.  We also plan to apply our PSMA technology,  including
therapeutics and in vitro  diagnostics,  toward other types of cancer based upon
our experience in prostate  cancer.  Our in vivo  immunotherapeutic  development
program is being conducted in collaboration with Progenics Pharmaceuticals, Inc.

Proteomics is the study of the expression and interaction of proteins.  Genomics
is the study and identification of an organism's genetic makeup.  While genomics
provides  important  information  regarding genetic makeup, it does not directly
provide  information   regarding  protein  functions  or  protein  interactions.
However,  genomics data can prove useful in  proteomics  research as a source of
obtaining  complete  protein  sequences  of ligands we have  identified.  Public
availability of this genomics  information  allows for effective  integration in
our database of public and  proprietary  information.  We recognized in our past
research that the key to  understanding  or developing the means to intervene in
diseases was primarily based on understanding  protein  interactions rather than
only through the use or study of genomics. We undertook this approach on our own
initiative and with our own funds. Our proteomics program,  under development by
our subsidiary, AxCell Biosciences Corporation, is focused on the identification
of protein  interaction  and  signaling  pathways  within  cells as  relating to
disease processes.

We   utilize   our   proprietary   proteomics   technology   to  map   selective
protein-protein   interactions   and  to   develop  a   database,   called   the
Inter-Functional  Proteomic  Database,  or IFP  Database,  which  includes  data
relating  to  protein   signaling   pathways   linked  to  a  variety  of  other
bioinformatic  data.  The IFP  Database  is  designed  to  permit  customers  to
integrate existing databases, both public and proprietary,  with our proprietary
data to create a 'virtual  laboratory'  on the computer  desktop of  researchers
involved in drug discovery.  We believe this database has significant  potential
commercial value to the pharmaceutical  and biotechnology  industries as a means
of expediting drug target  identification,  validation,  screen  development and
lead compound  optimization faster and cheaper than with current  methodologies.
These proprietary  technologies are designed to provide a platform from which we
can quickly and  cost-effectively  determine  protein-protein  interactions  and
build pathways of  intracellular  signaling data. Our IFP Database also offers a
consolidated platform to enable statistical and mathematical modeling of complex
protein pathways.

                                        3




RISK FACTORS

You should carefully consider the risks described below together with all of the
other information included in or incorporated by reference into this prospectus,
a prospectus  supplement or amendment before making an investment  decision.  If
any of the following risks occurs, our business,  financial condition or results
of  operations  could be harmed.  In that case,  the trading price of our common
stock could decline, and you may lose all or part of your investment.

WE HAVE A HISTORY OF  OPERATING  LOSSES AND  ACCUMULATED  DEFICIT  AND EXPECT TO
INCUR LOSSES IN THE FUTURE.

We have a history of operating losses since our inception.  We had net losses of
$1,961,000  during the three months  ended March 31, 2000.  We had net income of
$729,000  during  the year  ended  December  31,  1999  which  included  certain
non-operating  gains.  We had net  losses of  $13,152,000  during the year ended
December 31, 1998 and  $30,712,000  during the year ended  December 31, 1997. We
had an  accumulated  deficit of  $303,244,000  as of March 31, 2000. In order to
develop and commercialize our technologies,  particularly our proteomics program
and prostate  specific  membrane antigen,  or PSMA,  technology,  and expand our
oncology products, we expect to incur significant increases in our expenses over
the next several years. As a result,  we may continue to report operating losses
for the near  future  and we may  never be  profitable  or  achieve  significant
revenues.

Our ability to achieve significant revenues or profitability will depend upon
numerous factors, including:

o    successful product development;

o    our ability to acquire,  develop and commercialize  complementary  products
     and technologies; and

o    our ability to achieve  increased sales for our existing products and sales
     for any new products.

WE  ARE  IN  THE  EARLY  STAGES  OF  DEVELOPMENT  AND  COMMERCIALIZATION  OF OUR
TECHNOLOGY PLATFORMS AND MAY NEVER ACHIEVE THE GOALS OF OUR BUSINESS PLAN.

Early last year, we completed our  restructuring  to focus on development of our
prostate specific membrane antigen, or PSMA, and proteomics technologies and the
marketing of our existing products. We may be unable to continue to successfully
develop or commercialize these technologies.  Our PSMA and proteomics technology
are still in the early stages of  development.  We have only  recently  begun to
incorporate our proteomics technology into commercializable products.

We began operations in 1980 and have been engaged primarily in research directed
toward the development,  commercialization  and marketing of products to improve
diagnosis  and  treatment  of cancer and other  disease.  In December  1992,  we
introduced for commercial use our OncoScint  imaging agent.  In October 1996, we
introduced for commercial use our  ProstaScint  imaging agent. In March 1997, we
introduced for commercial use our Quadramet therapeutic product.  These products
have not yet  achieved  significant  commercial  success.  In  1998,  we began a
restructuring  of our  company  to  focus  on the  development  of our  PSMA and
proteomics technologies and marketing of these existing products.

Our business is therefore subject to the risks inherent in the development of an
early stage business enterprise, such as the need:

o    to obtain  sufficient  capital to support the  expenses of  developing  our
     technology and commercializing our products;

o    to ensure that our products are safe and effective;

o    to  manufacture  our products in sufficient  quantities and at a reasonable
     cost;

o    to develop a sufficient market for our products; and

o    to attract and retain qualified management, sales, technical and scientific
     staff.

                                       4




The problems  frequently  encountered  using new technologies and operating in a
competitive  environment  also may affect our  business.  If we fail to properly
address these risks and attain our business objectives, our business, results of
operations and financial condition will suffer.

OUR PROTEOMICS PROGRAM IS AT AN EARLY STAGE OF DEVELOPMENT.

We have developed and intend to continue to develop our proteomics program. This
technology  involves  new  approaches  and remains  commercially  unproven.  Our
technology  and  development  focus is  primarily  directed  toward  offering an
infrastructure  to companies for the  development of drugs to treat a variety of
complex human diseases. There is limited understanding generally relating to the
role of proteins in  diseases,  and few  products  based on protein  interaction
discoveries  have been  developed  and  commercialized.  Even if our  proteomics
program was successful in identifying and validating  biological targets,  there
is no  guarantee  that our  customers  will be able to develop or  commercialize
products to improve human health.

In  addition,  the  success of our  proteomics  technology  will depend upon our
ability to use software  tools to generate data that relates  protein  signaling
pathways  to a  variety  of  other  bioinformatic  information.  Because  of the
complexity  of this  data,  we may not be able to detect  and  remedy any design
defects or software  errors in our  existing or future  technologies,  including
databases.

Due to the  specialized  nature  and  price  of our  proteomics  technology  and
services,  there  are a  limited  number  of  pharmaceutical  and  biotechnology
companies that are potential customers.  Additional reasons why there may not be
a great demand for our proteomics technology and services include:

o    our potential customers may determine to conduct in-house research;

o    our competitors may offer similar services at competitive prices;

o    we may not be able to service  satisfactorily the needs of our potential or
     actual customers;

o    others may publicly disclose or patent proprietary information contained in
     our IFP  Database  (including  information  related  to  protein  signaling
     pathways  or  target  candidates)  or  relating  to  prostate  antigens  or
     antibodies; and

o    technological  innovations  may be  discovered  that are more advanced than
     those used by or available to us.

Our  technology  program  for  proteomics  is  still  in  the  early  stages  of
development.  We may not be able to populate our IFP Database  with  information
that is useful to potential  customers in a timely  manner.  Even if we complete
and develop  successfully our proteomics  technology,  the technology may not be
accepted by, or be useful to, our customers.

OUR PSMA  PRODUCT  DEVELOPMENT  PROGRAM IS NOVEL AND,  CONSEQUENTLY,  INHERENTLY
RISKY.

We are subject to the risks of failure  inherent in the  development  of product
candidates based on new technologies, including our PSMA technology. These risks
include the possibility that:

o    the technologies we use will not be effective;

o    our  product  candidates  will be unsafe or  otherwise  fail to receive the
     necessary regulatory approvals;

o    our product candidates will be hard to manufacture on a large scale or will
     be uneconomical to market; and

o    we will not successfully overcome technological challenges presented by our
     products.

Our  objectives  include  developing  our  PSMA  technology  into  novel  cancer
therapeutics,   including  a  cancer  vaccine.  To  our  knowledge,   no  cancer
therapeutic  vaccine has been  approved for  marketing.  Our other  research and
development  programs involve similarly novel approaches to human  therapeutics.
Consequently,  there is no precedent  for the  successful  commercialization  of
therapeutic  products based on our PSMA technologies.  We cannot assure you that
any of our products will be successfully developed.

                                       5




WE ARE HEAVILY  DEPENDENT ON MARKET  ACCEPTANCE OF PROSTASCINT AND QUADRAMET FOR
NEAR-TERM REVENUES.

ProstaScint  and Quadramet are expected to account for a significant  percentage
of our  product-related  revenues in the near future. For the three months ended
March  31,  2000,   revenues  from  ProstaScint  and  Quadramet   accounted  for
approximately 93% of our product related revenues.

Because these products contribute the majority of our product-related  revenues,
our business,  financial  condition  and results of  operations  depend on their
acceptance as safe, effective and cost-efficient alternatives to other available
treatment and diagnostic protocols by the medical community, including:

o    health care providers, such as hospitals and physicians; and

o    third-party  payors,  including  Medicare,   Medicaid,   private  insurance
     carriers and health maintenance organizations.

Our  customers,   including  technologists  and  physicians,  must  successfully
complete our Partners in  Excellence  Program,  or PIE  Program,  a  proprietary
training program designed to promote the correct  acquisition and interpretation
of ProstaScint  images.  This approach is,  therefore,  technique  dependent and
requires a learning  commitment on the part of users.  We cannot assure you that
additional physicians will make this commitment or otherwise accept this product
as part of their treatment practices.

Berlex  Laboratories,  Inc.  markets  Quadramet in the United States  through an
agreement that we entered into in October 1998. We cannot assure you that Berlex
will be able to successfully market Quadramet or that this agreement will result
in  significant  revenues  for us.  We  recently  obtained  marketing  rights to
Quadramet in Canada,  but have not yet implemented a selling program.  We cannot
assure you that Quadramet can be marketed effectively in Canada, or that it will
contribute significantly to our revenues.

We cannot assure you that Quadramet will be approved for additional indications,
due to  uncertainty as to efficacy or safety for other  purposes,  to regulatory
obstacles and to physician preferences for existing or competing practices.

Accordingly,  we cannot assure you that  ProstaScint  or Quadramet  will achieve
market  acceptance on a timely basis,  or at all. If ProstaScint or Quadramet do
not achieve broad market acceptance,  we may not be able to generate  sufficient
product revenue to become profitable.

WE MAY NEED TO RAISE ADDITIONAL CAPITAL WHICH MAY NOT BE AVAILABLE.

We have incurred  negative cash flows from operations since  inception.  We have
expended, and will need to continue to expend, substantial funds to complete our
planned product development efforts, including our proteomics and PSMA programs.
Our future capital  requirements  and the adequacy of our available funds depend
on many factors, including:

o    successful commercialization of our products;

o    acquisition of complementary products and technologies;

o    magnitude, scope and results of our product development efforts;

o    progress of preclinical studies and clinical trials;

o    progress of regulatory affairs activities;

o    costs of filing,  prosecuting,  defending and  enforcing  patent claims and
     other intellectual property rights;

o    competing technological and market developments; and

o    expansion of strategic  alliances for the sale,  marketing and distribution
     of our products.

                                       6




We may raise additional capital through public or private equity offerings, debt
financings or additional  collaborations and licensing arrangements.  Additional
financing may not be available to us when we need it, or, if  available,  we may
not be able to obtain financing on terms favorable to us or our stockholders. If
we raise  additional  capital by issuing  equity  securities,  the issuance will
result in ownership  dilution to our stockholders.  If we raise additional funds
through  collaborations  and  licensing  arrangements,  we  may be  required  to
relinquish  rights to certain of our  technologies  or product  candidates or to
grant licenses on unfavorable  terms. If we relinquish  rights or grant licenses
on  unfavorable  terms,  we may not be able to develop or market  products  in a
manner that is profitable to us. If adequate funds are not available, we may not
be able to conduct research activities,  preclinical studies, clinical trials or
other activities relating to the successful commercialization of our products.

COMPETITION IN OUR FIELD IS INTENSE AND LIKELY TO INCREASE.

We face, and will continue to face, intense  competition from one or more of the
following entities:

o    pharmaceutical companies;

o    biotechnology companies;

o    bioinformatics companies;

o    diagnostic companies;

o    academic and research institutions; and

o    government agencies.

All of our  lines of  business  are  subject  to  significant  competition  from
organizations  that are pursuing  technologies and products that are the same as
or similar to our technology and products.  Many of the organizations  competing
with us have greater  capital  resources,  research and  development  staffs and
facilities and marketing capabilities.

We believe  that our future  success will depend in large part on our ability to
maintain a competitive position in proteomics and in the development of oncology
products.   Before  we  recover  development   expenses  for  our  products  and
technologies,  the products or  technologies  may become obsolete as a result of
technological  developments  by us or others.  Our  products  could also be made
obsolete by new technologies which are less expensive or more effective.  We may
not be able to make the  enhancements  to our  technology  necessary  to compete
successfully with newly emerging technologies.

WE HAVE EXPERIENCED FLUCTUATING RESULTS OF OPERATIONS.

Our results of operations  have  fluctuated on an annual and quarterly basis and
may fluctuate  significantly  from period to period in the future, due to, among
other factors:

o    variations in revenue from sales of and royalties from our products;

o    timing of regulatory approvals and other regulatory  announcements relating
     to our products;

o    variations in our marketing, manufacturing and distribution channels;

o    timing of the  acquisition  and  successful  integration  of  complementary
     products and technologies;

o    timing  of new  product  announcements  and  introductions  by us  and  our
     competitors; and

o    product obsolescence resulting from new product introductions.

Many of these factors, and others not listed above, are outside our control. Due
to one or more of these  factors,  our results of operations  may fall below the
expectations  of  securities  analysts  and  investors  in  one or  more  future
quarters. If this happens, the market price of our common stock could decline.

                                       7



WE RELY HEAVILY ON OUR COLLABORATIVE PARTNERS.

Our success  depends in significant  part upon the success of our  collaborative
partners.  We  have  entered  into  the  following  agreements  for  the  sales,
marketing,  distribution and manufacture of our products, product candidates and
technologies:

o    sub-license and marketing agreement with Berlex Laboratories, Inc. relating
     to the  Quadramet  technology  which  we  licensed  from  The Dow  Chemical
     Company. Berlex is responsible for marketing, selling and arranging for the
     manufacture  and  distribution  of  Quadramet  in the United  States.  This
     agreement  expires on the later of October 28, 2018 or upon the  expiration
     of the patents covering Quadramet;

o    agreement  for  manufacture  of  Quadramet  by The  DuPont  Pharmaceuticals
     Company  (formerly  the  radiopharmaceuticals  division of The DuPont Merck
     Company);

o    marketing and platform development agreement with Informax, Inc. related to
     our proteomics program;

o    a joint venture with Progenics Pharmaceuticals, Inc. for the development of
     PSMA for immunotherapy for prostate and other cancers; and

o    letter of intent for a licensing agreement with Molecular Staging, Inc. for
     technology to be used in developing  in vitro  diagnostic  tests using PSMA
     and PSA.

Because our  collaborative  partners are  responsible  for certain of our sales,
marketing,  manufacturing  and  distribution  activities,  these  activities are
outside our direct control.  We cannot assure you that our partners will perform
their  obligations  under  these  agreements  with  us.  In the  event  that our
collaborative  partners  do not  successfully  market and sell our  products  or
breach  their  obligations  under  our  agreements,  our  products  may  not  be
commercially successful,  any success may be delayed and new product development
could be inhibited.

OUR  BUSINESS  COULD BE HARMED IF OUR  COLLABORATIONS  EXPIRE OR ARE  TERMINATED
EARLY.

We cannot assure you that we will be able to maintain our existing collaborative
arrangements.  If they expire or are terminated,  we cannot assure you that they
will be renewed or that new arrangements  will be available on acceptable terms,
if at all.  In  addition,  we cannot  assure  you that any new  arrangements  or
renewals of existing  arrangements  will be successful,  that the parties to any
new or  renewed  agreements  will  perform  adequately  or  that  any  potential
collaborators will not compete with us.

We cannot assure you that our existing or future collaborations will lead to the
development of product  candidates or technologies  with  commercial  potential,
that we will be able to obtain  proprietary  rights or licenses for  proprietary
rights for our product  candidates or technologies  developed in connection with
these  arrangements  or that we will be able to ensure  the  confidentiality  of
proprietary rights and information developed in such arrangements or prevent the
public disclosure thereof.

WE HAVE LIMITED SALES, MARKETING AND DISTRIBUTION CAPABILITIES FOR OUR PRODUCTS.

We recently established a sales force and have limited internal sales, marketing
and  distribution  capabilities  for our  products.  We depend on Berlex for the
sale, marketing and distribution of Quadramet in the United States. In locations
outside the United States, we have not established a selling presence. If we are
unable to establish and maintain  significant sales,  marketing and distribution
efforts,  either  internally or through  arrangements  with third  parties,  our
business may be harmed.

THERE ARE RISKS ASSOCIATED WITH THE MANUFACTURE OF OUR PRODUCTS.

If we are to be  successful,  our products will have to be  manufactured  either
internally or through  third-party  manufacturers  in compliance with regulatory
requirements and at costs acceptable to us. We cannot assure you that we will be
able to continue to manufacture,  arrange for manufacture on reasonable terms or
successfully  outsource the  manufacturing of our products.  If we are unable to
successfully  manufacture  or arrange for the  manufacture  of our  products and
product  candidates,  we would  not be able to  successfully  commercialize  our
products and our business may be seriously harmed.

                                       8




OUR BUSINESS MAY BE ADVERSELY  AFFECTED BY THE  UNCERTAINTY  ASSOCIATED WITH OUR
THIRD-PARTY MANUFACTURERS' DEPENDENCE ON SINGLE SOURCE SUPPLIERS.

Quadramet is  manufactured  by DuPont  pursuant to an agreement with both Berlex
and Cytogen. Some components of Quadramet,  particularly  Samarium153 and EDTMP,
are  provided  to  DuPont  by  outside  suppliers.  Due  to  radioactive  decay,
Samarium153 must be produced on a weekly basis.  DuPont obtains its requirements
for Samarium153 from one supplier.  Alternative sources for these components may
not be readily  available.  On one  occasion,  DuPont was unable to  manufacture
Quadramet  on a timely  basis due to the  failure  of its  supplier  to  provide
Samarium153.  If DuPont cannot obtain sufficient quantities of the components on
commercially  reasonable  terms,  or in a timely  manner,  it would be unable to
manufacture  Quadramet on a timely and  cost-effective  basis which could affect
our ability to generate sufficient revenues to become profitable.

COMPLIANCE WITH MANUFACTURING REGULATIONS IS CRITICAL TO OUR BUSINESS.

We and our  third-party  manufacturers  are required to adhere to US Food & Drug
Administration   regulations   setting  forth   requirements  for  current  Good
Manufacturing  Practices,  or cGMP, and similar  regulations in other countries,
which include extensive testing, control and documentation requirements. Ongoing
compliance with cGMP, labeling and other applicable regulatory  requirements are
monitored  through  periodic  inspections  and market  surveillance by state and
federal  agencies,  including  the  FDA,  and by  comparable  agencies  in other
countries.  Failure  of  our  third-party  manufacturers  or us to  comply  with
applicable  regulations could result in sanctions being imposed on us, including
fines,  injunctions,  civil  penalties,  failure  of  the  government  to  grant
premarket  clearance  or  premarket  approval of drugs,  delays,  suspension  or
withdrawal of approvals, seizures or recalls of products, operating restrictions
and criminal prosecutions.

FAILURE OF CONSUMERS TO OBTAIN ADEQUATE  REIMBURSEMENT  FROM THIRD-PARTY  PAYORS
COULD LIMIT MARKET  ACCEPTANCE AND AFFECT  PRICING OF OUR PRODUCTS,  WHICH WOULD
MATERIALLY ADVERSELY AFFECT OUR BUSINESS.

Our business,  financial condition and results of operations will continue to be
affected by the efforts of governments and other  third-party  payors to contain
or reduce the costs of  healthcare.  There have been,  and we expect  that there
will  continue  to be, a number of  federal  and state  proposals  to  implement
government  control of pricing and  profitability  of therapeutic and diagnostic
imaging  agents such as our products.  In addition,  an emphasis on managed care
increases  possible  pressure  on  pricing  of these  products.  While we cannot
predict whether these  legislative or regulatory  proposals will be adopted,  or
the effects  these  proposals or managed care efforts may have on our  business,
the  announcement  of these  proposals  and the  adoption of these  proposals or
efforts  could affect our stock price or our  business.  Further,  to the extent
these  proposals or efforts have a material  adverse  effect on other  companies
that are our prospective corporate partners,  our ability to establish strategic
alliances may be adversely affected.

Sales of our  products  depend in part on  reimbursement  to the  consumer  from
third-party payors,  including  Medicare,  Medicaid and private health insurance
plans.  Third-party  payors are increasingly  challenging the prices charged for
medical  products and  services.  We cannot assure you that our products will be
considered  cost-effective  and that reimbursement to consumers will continue to
be  available,  or will be  sufficient  to allow us to sell  our  products  on a
competitive  basis.  Approval of our products for reimbursement by a third-party
payor may depend on a number of factors,  including  the  payor's  determination
that our products are clinically useful and cost-effective,  medically necessary
and not  experimental or  investigational.  Reimbursement  is determined by each
payor individually and in specific cases. The reimbursement  process can be time
consuming.  If we  cannot  secure  adequate  third-party  reimbursement  for our
products,  there would be a material  adverse effect on our business,  financial
condition and results of operations.

OUR POTENTIAL ONCOLOGY PRODUCTS WILL BE SUBJECT TO THE RISKS OF FAILURE INHERENT
IN  THE  DEVELOPMENT  OF  DIAGNOSTIC  OR  THERAPEUTIC   PRODUCTS  BASED  ON  NEW
TECHNOLOGIES.

Product  development  involves a high degree of risk.  We cannot assure you that
the product  candidates  we  develop,  pursue or offer will prove to be safe and
effective,  will  receive  the  necessary  regulatory  approvals,  will  not  be
precluded by  proprietary  rights of third  parties or will  ultimately  achieve
market acceptance.  These product candidates will require substantial additional
investment,  laboratory  development,  clinical testing and regulatory approvals
prior  to  their  commercialization.  We  cannot  assure  you  that we will  not
experience  difficulties that could

                                       9




delay or prevent the successful  development,  introduction and marketing of new
products.  If we are unable to develop  and  commercialize  products on a timely
basis or at all, our business will be harmed.

Before we obtain  regulatory  approvals  for the  commercial  sale of any of our
products under development,  we must demonstrate through preclinical studies and
clinical  trials that the product is safe and efficacious for use in each target
indication.  The results from preclinical  studies and early clinical trials may
not be predictive of results that will be obtained in  large-scale  testing.  We
cannot  assure you that our  clinical  trials  will  demonstrate  the safety and
efficacy  of any  products or will result in  marketable  products.  A number of
companies in the biotechnology  industry have suffered  significant  setbacks in
advanced  clinical  trials,  even after  promising  results  in earlier  trials.
Clinical trials or marketing of any potential diagnostic or therapeutic products
may expose us to liability claims for the use of these diagnostic or therapeutic
products.  We may not be able to  obtain  product  liability  insurance  or,  if
obtained,  sufficient  coverage may not be available  at a reasonable  cost.  In
addition,  as we develop diagnostic or therapeutic products internally,  we will
have to make  significant  investments  in  diagnostic  or  therapeutic  product
development,  marketing, sales and regulatory compliance resources. We will also
have to  establish  or  contract  for the  manufacture  of  products,  including
supplies of drugs used in clinical trials,  under the current Good Manufacturing
Practices  of the FDA. We also cannot  assure you that  product  issues will not
arise following successful clinical trials and FDA approval.

The rate of  completion  of clinical  trials also depends on the rate of patient
enrollment.  Patient enrollment  depends on many factors,  including the size of
the patient population, the nature of the protocol, the proximity of patients to
clinical  sites and the  eligibility  criteria for the study.  Delays in planned
patient enrollment may result in increased costs and delays,  which could have a
harmful effect on our ability to develop the products in our pipeline.

IF WE ARE UNABLE TO COMPLY WITH APPLICABLE GOVERNMENTAL REGULATIONS,  WE MAY NOT
BE ABLE TO CONTINUE OUR OPERATIONS.

Any products tested, manufactured or distributed by us or on our behalf pursuant
to  FDA  clearances  or  approvals  are  subject  to  pervasive  and  continuing
regulation by numerous regulatory  authorities,  including primarily the FDA. We
may be slow to adapt, or we may never adapt to changes in existing  requirements
or  adoption  of new  requirements  or  policies.  Our  failure  to comply  with
regulatory  requirements  could  subject  us to  enforcement  action,  including
product seizures, recalls,  withdrawal of clearances or approvals,  restrictions
on or injunctions  against  marketing our products based on our technology,  and
civil and criminal penalties.  We cannot assure you that we will not be required
to incur  significant costs to comply with laws and regulations in the future or
that  laws or  regulations  will  not  create  an  unsustainable  burden  on our
business.

Numerous federal, state and local governmental authorities, principally the FDA,
and similar  regulatory  agencies in other  countries,  regulate the preclinical
testing,  clinical trials,  manufacture and promotion of any compounds or agents
we or our collaborative partners develop, and the manufacturing and marketing of
any resulting  drugs.  The drug  development and regulatory  approval process is
lengthy, expensive, uncertain and subject to delays.

The regulatory risks we face also include the following:

o    any compound or agent we or our collaborative partners develop must receive
     regulatory  agency  approval  before  it may  be  marketed  as a drug  in a
     particular country;

o    the regulatory  process,  which includes  preclinical  testing and clinical
     trials of each  compound  or agent in order to  establish  its  safety  and
     efficacy,  varies from country to country, can take many years and requires
     the expenditure of substantial resources;

o    in  all  circumstances,  approval  of  the  use  of  previously  unapproved
     radioisotopes  in certain of our products  requires  approval of either the
     Nuclear Regulatory  Commission or equivalent state regulatory  agencies.  A
     radioisotope is an unstable form of an element which undergoes  radioactive
     decay,  thereby emitting radiation which may be used, for example, to image
     or  destroy  harmful  growths  or  tissue.  We cannot  assure you that such
     approvals will be obtained on a timely basis, or at all;

o    data obtained from  preclinical and clinical  activities are susceptible to
     varying  interpretations  which could  delay,  limit or prevent  regulatory
     agency approval; and

                                       10




o    delays or rejections  may be  encountered  based upon changes in regulatory
     agency  policy during the period of drug  development  and/or the period of
     review of any  application  for regulatory  agency  approval.  These delays
     could   adversely   affect  the   marketing  of  any  products  we  or  our
     collaborative   partners   develop,   impose  costly  procedures  upon  our
     activities,   diminish  any  competitive  advantages  we  or  collaborative
     partners may attain and adversely affect our ability to receive royalties.

We cannot  assure you that,  even after  this time and  expenditure,  regulatory
agency  approvals will be obtained for any compound or agent  developed by or in
collaboration with us. Moreover,  regulatory agency approval for a drug or agent
may entail  limitations  on the  indicated  uses that could limit the  potential
market for any such drug.  Furthermore,  if and when such  approval is obtained,
the marketing, manufacture,  labeling, storage and record keeping related to our
products would remain subject to extensive regulatory requirements. Discovery of
previously unknown problems with a drug, its manufacture or its manufacturer may
result in  restrictions  on such drug,  manufacture or  manufacturer,  including
withdrawal  of the drug  from the  market.  Failure  to comply  with  regulatory
requirements  could  result  in  fines,   suspension  of  regulatory  approvals,
operating restrictions and criminal prosecution.

The US Food,  Drug and Cosmetics Act requires that our products be  manufactured
in FDA registered facilities subject to inspection.  The manufacturer must be in
compliance  with  cGMP,  which  imposes  certain  procedural  and  documentation
requirements   upon  us,  and  our   manufacturing   partners  with  respect  to
manufacturing  and  quality  assurance  activities.  If we or our  manufacturing
partners  do not  comply  with cGMP we may be subject  to  sanctions,  including
fines, injunctions,  civil penalties,  recalls or seizures of products, total or
partial  suspension of production,  failure of the government to grant premarket
clearance or premarket approval for drugs, withdrawal of marketing approvals and
criminal prosecution.

WE DEPEND ON ATTRACTING AND RETAINING KEY PERSONNEL.

We are  highly  dependent  on  the  principal  members  of  our  management  and
scientific  staff.  The  loss of their  services  might  significantly  delay or
prevent the  achievement  of development  or strategic  objectives.  Our success
depends  on our  ability  to retain  key  employees  and to  attract  additional
qualified employees.  Competition for personnel is intense, and we cannot assure
you that we will be able to retain  existing  personnel  or  attract  and retain
additional highly qualified employees in the future.

We have an employee  retention  agreement with our President and Chief Executive
Officer,  H. Joseph Reiser,  Ph.D.,  which provides for vesting of stock options
for the purchase of shares of our common stock based on continued employment and
on the achievement of performance  objectives defined by the board of directors.
We do not have similar retention agreements with our other key personnel.  If we
are unable to hire and retain  personnel in key  positions,  our  management and
operations will suffer unless a qualified replacement can be found.

OUR  BUSINESS  EXPOSES  US TO  POTENTIAL  LIABILITY  CLAIMS  THAT MAY EXCEED OUR
FINANCIAL  RESOURCES,  INCLUDING  OUR  INSURANCE  COVERAGE,  AND MAY LEAD TO THE
CURTAILMENT OR TERMINATION OF OUR OPERATIONS.

Our  business is subject to product  liability  risks  inherent in the  testing,
manufacturing  and marketing of our products.  We cannot assure you that product
liability  claims will not be  asserted  against  us, our  collaborators  or our
licensees. While we currently maintain product liability insurance in amounts we
believe are  adequate,  we cannot assure you that such coverage will be adequate
to protect us against future product  liability claims or that product liability
insurance  will be  available  to us in the  future on  commercially  reasonable
terms,  if at all.  Furthermore,  we cannot  assure  you that we will be able to
avoid significant  product liability claims and adverse publicity.  If liability
claims  against  us exceed  our  financial  resources  we may have to curtail or
terminate our operations.

OUR BUSINESS INVOLVES ENVIRONMENTAL RISKS THAT MAY RESULT IN LIABILITY FOR US.

We are subject to a variety of local, state and federal  government  regulations
relating to storage, discharge, handling, emission, generation,  manufacture and
disposal of toxic,  infectious or other hazardous substances used to manufacture
our products.  If we fail to comply with these  regulations,  we could be liable
for damages, penalties or other forms of censure.

                                       11




IF OUR PATENT APPLICATIONS DO NOT RESULT IN ISSUED PATENTS, THEN OUR COMPETITORS
MAY OBTAIN RIGHTS TO COMMERCIALIZE OUR DISCOVERIES.

Our business and competitive positions are dependent upon our ability to protect
our  proprietary  technology.  Because  of the  substantial  length  of time and
expense  associated with  development of new products,  we, like the rest of the
biopharmaceutical  industry,  place  considerable  importance  on obtaining  and
maintaining  patent and trade secret protection for new  technologies,  products
and  processes.  We  have  filed  patent  applications  for our  technology  for
diagnostic  and  therapeutic  products and the methods for their  production and
use.

The patent  positions of  pharmaceutical,  biopharmaceutical  and  biotechnology
companies,  including us, are generally  uncertain and involve complex legal and
factual questions.  Our patent applications may not protect our technologies and
products because of the following reasons:

o    there is no  guarantee  that any of our pending  patent  applications  will
     result in additional issued patents;

o    we may develop additional proprietary technologies that are not patentable;

o    there is no guarantee that any patents issued to us, our  collaborators  or
     our licensors will provide a basis for a commercially viable product;

o    there is no guarantee  that any patents  issued to us or our  collaborators
     will provide us with any competitive advantage;

o    there is no guarantee  that any patents  issued to us or our  collaborators
     will not be challenged, circumvented or invalidated by third parties; and

o    there is no  guarantee  that any  patents  previously  issued  to others or
     issued in the future  will not have an adverse  effect on our ability to do
     business.

In  addition,  patent  law in the  technology  fields  in  which we  operate  is
uncertain  and still  evolving,  and we cannot  assure  you as to the  degree of
protection  that will be  afforded  any  patents we are  issued or license  from
others.  Furthermore,  we cannot  assure you that others will not  independently
develop similar or alternative technologies,  duplicate any of our technologies,
or, if  patents  are  issued to us,  design  around  the  patented  technologies
developed by us. In addition,  we could incur substantial costs in litigation if
we are required to defend  ourselves  in patent suits by third  parties or if we
initiate  such suits.  We cannot  assure you that,  if  challenged  by others in
litigation,  the patents we have been issued,  or which we have been assigned or
have licensed from others will not be found  invalid.  We cannot assure you that
our  activities  would  not  infringe  patents  owned  by  others.  Defense  and
prosecution  of  patent  matters  can  be  expensive  and  time-consuming   and,
regardless  of  whether  the  outcome  is  favorable  to us,  can  result in the
diversion of substantial financial,  managerial and other resources.  An adverse
outcome could:

o    subject us to significant liability to third parties;

o    require us to cease any related  research and  development  activities  and
     product sales; or

o    require us to obtain licenses from third parties.

We cannot  assure  you that any  licenses  required  under any such  third-party
patents or proprietary rights would be made available on commercially reasonable
terms, if at all.  Moreover,  the laws of certain  countries may not protect our
proprietary rights to the same extent as US law.

THE ISSUANCE OF PATENTS MAY NOT PROVIDE US WITH SUFFICIENT PROTECTION.

We depend on our patents and proprietary rights. The issuance of a patent is not
conclusive as to its validity or enforceability,  nor does it provide the patent
holder with freedom to operate  without  infringing the patent rights of others.
Our patents and the patents we license could be challenged by litigation and, if
the outcome of such litigation was adverse, competitors could be free to use the
subject matter covered by the patent, or we may license the technology to others
in  settlement  of  such   litigation.   Invalidation  of  our  key  patents  or
non-approval  of pending  patent  applications  could increase  competition.  In
addition,  any  application or  exploitation  of our  technology  could

                                       12




infringe patents or proprietary  rights of others and any licenses that we might
need  as a  result  of  such  infringement  might  not  be  available  to  us on
commercially reasonable terms, if at all.

We cannot predict whether our or our  competitors'  pending patent  applications
will result in the issuance of valid patents.  Litigation, which could result in
substantial  cost to us,  may  also be  necessary  to  enforce  our  patent  and
proprietary  rights  and/or  to  determine  the scope and  validity  of  others'
proprietary  rights. We may participate in interference  proceedings that may in
the future be declared by the Patent and Trademark Office to determine  priority
of invention,  which could result in substantial  cost to us. The outcome of any
litigation or interference proceeding might not be favorable to us, and we might
not be able to obtain  licenses to  technology  that we require at a  reasonable
cost, if at all.

We are a defendant in litigation  filed against us in the United States  Federal
Court for the District of New Jersey by M. David  Goldenberg  and  Immunomedics,
Inc. This lawsuit was filed on March 16, 2000.  The  litigation  claims that our
ProstaScint  product infringes a patent  purportedly owned by Dr. Goldenburg and
licensed to  Immunomedics.  We believe that the  purported  patent  sought to be
enforced in the  litigation  has now expired.  As a result,  the claim,  even if
successful,  would not result in a bar of the continued  sale of  ProstaScint or
affect any other of our products or technology.  However,  given the uncertainty
associated  with  litigation,  we cannot give any assurance  that the litigation
could not result in a material expenditure to us.

THE  TERMINATION  OF ONE OR MORE LICENSE  AGREEMENTS  THAT ARE  IMPORTANT IN THE
MANUFACTURE  OF OUR CURRENT  PRODUCTS AND NEW PRODUCT  RESEARCH AND  DEVELOPMENT
ACTIVITIES WOULD HARM OUR BUSINESS.

We are a  party  to  license  agreements  under  which  we  have  rights  to use
technologies  owned by other companies in the manufacture of our products and in
our  proprietary  research,  development  and  testing  processes.  We  are  the
exclusive  licensee  of  certain  patents  and patent  applications  held by the
University of North Carolina at Chapel Hill covering part of the technology used
in the proteomics program and of certain patents and patent applications held by
the  Memorial  Sloan-Kettering  Institute  covering  PSMA.  We  depend  upon the
enforceability  of our license  with The Dow  Chemical  Company  with respect to
Quadramet. If the licenses were terminated,  we may not be able to find suitable
alternatives  to this  technology on timely or reasonable  terms, if at all. The
loss  of the  right  to use  these  technologies  that we  have  licensed  would
significantly harm our business.

WE  CANNOT  BE  CERTAIN  THAT  OUR  SECURITY  MEASURES  PROTECT  OUR  UNPATENTED
PROPRIETARY TECHNOLOGY.

We also rely upon  trade  secret  protection  for some of our  confidential  and
proprietary  information that is not subject matter for which patent  protection
is  being  sought.  To help  protect  our  rights,  we  require  all  employees,
consultants, advisors and collaborators to enter into confidentiality agreements
that require  disclosure,  and in most cases,  assignment to us, of their ideas,
developments,  discoveries and  inventions,  and that prohibit the disclosure of
confidential  information  to anyone  outside  Cytogen.  We cannot  assure  you,
however,  that these agreements will provide  adequate  protection for our trade
secrets,  know-how  or  other  proprietary  information  in  the  event  of  any
unauthorized use or disclosure.

IF WE MAKE ANY  ACQUISITIONS,  WE WILL  INCUR A  VARIETY  OF COSTS AND MAY NEVER
REALIZE THE ANTICIPATED BENEFITS.

If  appropriate  opportunities  become  available,  we may  attempt  to  acquire
businesses,  technologies,  services or products that we believe are a strategic
fit with our business.  We currently  have no  commitments  or  agreements  with
respect to any acquisitions other than those described in this prospectus. If we
do  undertake  any  transaction  of this sort,  the  process of  integrating  an
acquired  business,  technology,  service  or product  may  result in  operating
difficulties and expenditures and may absorb  significant  management  attention
that would  otherwise  be available  for ongoing  development  of our  business.
Moreover,  we may never  realize the  anticipated  benefits of any  acquisition.
Future  acquisitions  could result in potentially  dilutive  issuances of equity
securities,  the incurrence of debt,  contingent  liabilities  and  amortization
expenses  related to goodwill and other intangible  assets.  These factors could
adversely affect our results of operations and financial condition,  which could
cause a decline in the market price of our common stock.

                                       13




WE MAY INVEST OR SPEND THE PROCEEDS OF THIS  OFFERING IN WAYS WITH WHICH YOU MAY
NOT AGREE.

We will retain broad discretion over the use of proceeds from this offering. You
may not agree with how we spend the  proceeds,  and our use of the  proceeds may
not yield a significant return or any return at all. We intend to use a majority
of the proceeds from this offering to fund our operations,  including  continued
development, manufacturing and commercialization of our proteomics technologies,
research and  development  of  additional  products,  expansion of our sales and
marketing  capabilities,  and for general corporate purposes,  including working
capital  and  capital  expenditures.  Because of the number and  variability  of
factors that determine our use of the net proceeds from this offering, we cannot
assure  you that  these  uses  will not vary  substantially  from our  currently
planned  uses.  Until we use the net  proceeds  of this  offering  for the above
purposes,  we intend to invest the funds in investment  grade,  interest bearing
securities.

OUR STOCK PRICE HAS BEEN AND MAY CONTINUE TO BE VOLATILE, AND YOUR INVESTMENT IN
OUR STOCK COULD DECLINE IN VALUE.

The market prices for securities of biotechnology and  pharmaceutical  companies
have  historically  been highly  volatile,  and the market has from time to time
experienced  significant price and volume fluctuations that are unrelated to the
operating  performance of particular  companies.  The market price of our common
stock has fluctuated over a wide range and may continue to fluctuate for various
reasons, including, but not limited to, announcements concerning our competitors
or us regarding:

o    results of clinical trials;

o    technological innovations or new commercial products;

o    changes  in  governmental  regulation  or  the  status  of  our  regulatory
     approvals or applications;

o    changes in earnings;

o    changes in health care policies and practices;

o    developments or disputes concerning proprietary rights;

o    litigation or public  concern as to the safety of our  potential  products;
     and

o    changes in general market conditions.

WE HAVE ADOPTED  VARIOUS  ANTI-TAKEOVER  PROVISIONS  WHICH MAY AFFECT THE MARKET
PRICE OF OUR COMMON STOCK.

Our Board of Directors has the authority,  without further action by the holders
of common stock, to issue from time to time, up to 5,400,000 shares of preferred
stock in one or more classes or series, and to fix the rights and preferences of
the  preferred  stock.  Pursuant  to these  provisions,  we have  implemented  a
stockholder  rights plan by which one preferred stock purchase right is attached
to each share of common stock, as a means to deter coercive takeover tactics and
to prevent an acquirer  from  gaining  control of us without  some  mechanism to
secure a fair price for all of our stockholders if an acquisition was completed.
These  rights  will be  exercisable  if a person  or group  acquires  beneficial
ownership  of 20% or more of our  common  stock and can be made  exercisable  by
action of our board of directors  if a person or group  commences a tender offer
which would  result in such person or group  beneficially  owning 20% or more of
our common stock.  Each right will entitle the holder to buy one  one-thousandth
of a share of a new series of our junior participating  preferred stock for $20.
If any person or group becomes the beneficial owner of 20% or more of our common
stock (with certain  limited  exceptions),  then each right not owned by the 20%
stockholder  will  entitle its holder to  purchase,  at the right's then current
exercise price, common shares having a market value of twice the exercise price.
In addition,  if after any person has become a 20% stockholder,  we are involved
in a merger or other business combination  transaction with another person, each
right will entitle its holder (other than the 20%  stockholder) to purchase,  at
the right's then current exercise price,  common shares of the acquiring company
having a value of twice the right's then current exercise price.

We are subject to provisions of Delaware corporate law which, subject to certain
exceptions,  will prohibit us from engaging in any "business combination" with a
person who,  together with  affiliates and  associates,  owns 15% or

                                       14




more of our common stock for a period of three years following the date that the
person  came  to own  15% or  more  of our  common  stock  unless  the  business
combination is approved in a prescribed manner.

These   provisions  of  the   stockholder   rights  plan,  our   certificate  of
incorporation, and of Delaware law may have the effect of delaying, deterring or
preventing a change in control of us, may  discourage  bids for our common stock
at a premium over market price and may adversely  affect the market  price,  and
the voting and other rights of the holders, of our common stock.

A LARGE NUMBER OF OUR SHARES ARE  ELIGIBLE  FOR FUTURE SALE WHICH MAY  ADVERSELY
IMPACT THE MARKET PRICE OF OUR COMMON STOCK.

A large number of shares of common stock already  outstanding,  or issuable upon
exercise of options and warrants,  are eligible for resale,  which may adversely
affect  the  market  price  of the  common  stock.  As of May  8,  2000,  we had
72,755,578 shares of common stock outstanding. An additional 4,567,566 shares of
common stock are issuable  upon the exercise of  outstanding  stock  options and
warrants  as  of  such  date.  Substantially  all  of  such  shares  subject  to
outstanding  options will, when issued upon exercise  thereof,  be available for
immediate   resale  in  the  public  market  pursuant  to  currently   effective
registration  statements  under  the  Securities  Act of 1933,  as  amended,  or
pursuant to Rule 701 promulgated thereunder.

Berlex  Laboratories,  Inc.  exercised its  registration  rights with respect to
1,000,000 shares of common stock and we are contractually  obligated to register
these shares. A registration statement with respect to these shares was filed on
April 11, 2000 and declared effective April 27, 2000.

                                       15




FORWARD-LOOKING STATEMENTS

This  prospectus  includes  forward-looking  statements  about our  business and
results of  operations  that are subject to risks and  uncertainties  that could
cause  our  actual  results  to vary  materially  from  those  reflected  in the
forward-looking  statements.  Words such as "believes,"  "anticipates," "plans,"
"estimates,"   "future,"   "could,"  "may,"  "should,"   "expect,"   "envision,"
"potentially,"  variations of such words and similar expressions are intended to
identify such forward-looking statements. Factors that could cause or contribute
to these differences include those discussed  previously under the caption "Risk
factors" and elsewhere in this prospectus.  Investors are cautioned not to place
undue reliance on these  forward-looking  statements  which speak only as of the
date   hereof.   We  disclaim   any  intent  or   obligation   to  update  these
forward-looking statements.

You  should  not  unduly  rely  on  forward-looking   statements   contained  or
incorporated  by reference in this  prospectus.  Actual  results or outcomes may
differ materially from those predicted in our forward-looking  statements due to
the risks and  uncertainties  inherent in our  business,  including  among other
items, risks and uncertainties in:

o    our ability to successfully execute our business model;

o    our  ability  to  compete   successfully   against   direct  and   indirect
     competitors;

o    our ability to launch our proteomics program successfully;

o    market acceptance of and continuing demand for our products;

o    our ability to develop new products;

o    our ability to protect our  intellectual  property,  including  patents and
     know-how;

o    our ability to obtain additional financing to support our operations;

o    the continuation of our corporate collaborations; and

o    changing market conditions and other risks detailed below.

You should read and interpret any  forward-looking  statements together with the
following documents:

o    our most recent Annual Report on Form 10-K;

o    the risk  factors  contained  in this  prospectus  under the caption  "Risk
     factors"; and

o    our other filings with the SEC.

Any forward-looking statement speaks only as of the date on which that statement
is made. We will not update any  forward-looking  statement to reflect events or
circumstances that occur after the date on which such statement is made.

                                       16




USE OF PROCEEDS

Unless the applicable  prospectus  supplement states  otherwise,  we will retain
broad  discretion  in the  allocation  of the net  proceeds  of  this  offering.
2,000,000  shares of common  stock  previously  registered  hereunder  have been
issued in the name of Advanced Magnetics,  Inc. in connection with the execution
by each of  Cytogen  and  Advanced  Magnetics  on August  25,  2000 of a certain
License and  Marketing  Agreement  and a certain  Supply  Agreement  relating to
certain of Advanced Magnetics' technology and proprietary  information.  500,000
of such  2,000,000  shares are being held in escrow,  to be released to Advanced
Magnetics  upon the  achievement  of  certain  milestones  under  the  licensing
arrangements.  2,179,158 additional shares of common stock previously registered
hereunder were issued in the name of Acqua  Wellington  North American  Equities
Fund,  Ltd.,  an  institutional  investor.  We  currently  intend to use the net
proceeds of this and any future issuances for:

o    continued   development,   manufacturing  and   commercialization   of  our
     proteomics  technologies  through  our  wholly-owned   subsidiary,   AxCell
     BioSciences Corporation;

o    research and development of additional  products,  including diagnostic and
     therapeutic products based upon our PSMA technology;

o    expansion of our sales and marketing capabilities; and

o    other general corporate purposes, including principally working capital and
     capital expenditures.

Pending  these uses,  we intend to invest the net  proceeds of this  offering in
investment grade, interest-bearing obligations.

                                       17




PLAN OF DISTRIBUTION

We may sell our common  stock to or through one or more  underwriters,  and also
may sell our common  stock  directly to other  purchasers  or through  agents or
dealers.  After the issuance of the 1,820,000 shares offered hereby to the State
of  Wisconsin   Investment  Board  and  the  4,179,158  shares  previously  sold
hereunder,  as set forth  below,  there  remain 842 shares of common stock to be
sold hereunder.

2,000,000 shares of common stock previously  registered hereunder were issued on
August 25, 2000 in the name of Advanced  Magnetics,  Inc. in connection with the
execution  by each of Cytogen and Advanced  Magnetics  of a certain  License and
Marketing  Agreement  and a certain  Supply  Agreement  relating  to  certain of
Advanced  Magnetics'  technology and  proprietary  information.  500,000 of such
2,000,000 shares are being held in escrow, to be released to Advanced  Magnetics
upon the achievement of certain milestones under the licensing arrangements. The
cost of registering such shares was borne by Cytogen.

902,601 shares of common stock  previously  registered  hereunder were issued on
September 29, 2000 in the name of Acqua Wellington North American Equities Fund,
Ltd., an institutional investor. Such common stock was purchased at a negotiated
price of  $5,999,996.  1,276,557  shares of common stock  previously  registered
hereunder were issued on February 5, 2001, also in the name of Acqua  Wellington
North  American  Equities  Fund,  Ltd.  Such  common  stock was  purchased  at a
negotiated  price of $6,500,000.  Each such aggregate  purchase price reflects a
small discount to the volume weighted  average pricing of our common stock based
on the  Nasdaq  National  Market.  We did  not  pay any  other  compensation  in
connection  with either such sale of our common stock.  The cost of  registering
such shares was and shall be borne by Cytogen  and we have  agreed to  indemnify
Acqua  Wellington and certain of its  affiliates  against  certain  liabilities,
including liabilities under the Securities Act of 1933, as amended.

The  1,820,000  shares of common stock  registered  hereunder in the name of the
State of Wisconsin  Investment  Board were  purchased  at a negotiated  price of
$8,190,000.  We did not pay any other  compensation in connection with such sale
of our common stock.  The cost of registering such shares was and shall be borne
by Cytogen and we have agreed to  indemnify  the State of  Wisconsin  Investment
Board and  certain of its  affiliates  against  certain  liabilities,  including
liabilities under the Securities Act of 1933, as amended.

Our common stock may be distributed in one or more transactions at a fixed price
or prices,  which may be changed,  at market  prices  prevailing  at the time of
sale,  at prices  related  to such  prevailing  market  prices or at  negotiated
prices.

Offers to purchase  common  stock may be  solicited  directly  by us.  Offers to
purchase common stock may also be solicited by agents designated by us from time
to time. Any such agent,  who may be deemed to be an  "underwriter" as that term
is defined in the Securities  Act of 1933,  involved in the offer or sale of our
common stock in respect of which this prospectus is delivered will be named, and
any commissions payable by us to such agent will be set forth, in the applicable
prospectus supplement.

If a dealer is utilized in the sale of our common stock in respect of which this
prospectus  is  delivered,  we will sell such  common  stock to the  dealer,  as
principal.  The dealer, who may be deemed to be an "underwriter" as that term is
defined in the  Securities Act of 1933, may then resell such common stock to the
public at varying prices to be determined by such dealer at the time of resale.

If an underwriter is, or underwriters are, utilized in the sale, we will execute
an underwriting  agreement with underwriters at the time of sale to them and the
names  of the  underwriters  will  be set  forth  in the  applicable  prospectus
supplement, which will be used by the underwriters to make resales of our common
stock in  respect  of which this  prospectus  is  delivered  to the  public.  In
connection with the sale of our common stock, underwriters may be deemed to have
received  compensation  from  us  in  the  form  of  underwriting  discounts  or
commissions and may also receive commissions from purchasers of our common stock
for whom they may act as agents.  Underwriters may also sell our common stock to
or  through  dealers,  and  dealers  may  receive  compensation  in the  form of
discounts,  concessions or commissions from the underwriters  and/or commissions
from  the  purchasers  for  whom  they  may  act  as  agents.  Any  underwriting
compensation  paid by us to  underwriters in connection with the offering of our
common  stock,  and  any  discounts,   concessions  or  commissions  allowed  by
underwriters  to  participating  dealers,  will be set  forth in the  applicable
prospectus supplement.

                                       18




Underwriters,   dealers,  agents  and  other  persons  may  be  entitled,  under
agreements  that may be entered into with us, to  indemnification  by us against
certain civil  liabilities,  including  liabilities  under the Securities Act of
1933, or to contribution  with respect to payments which they may be required to
make in respect  thereof.  Underwriters  and  agents may engage in  transactions
with, or perform services for, us in the ordinary course of business.

If so indicated  in the  applicable  prospectus  supplement,  we will  authorize
underwriters, dealers or other persons to solicit offers by certain institutions
to purchase our common stock  pursuant to  contracts  providing  for payment and
delivery on a future date or dates.  Institutions  with which  contracts  may be
made include commercial and savings banks,  insurance companies,  pension funds,
investment  companies,  educational and charitable  institutions and others. The
obligations  of any  purchaser  under any  contract  will not be  subject to any
conditions  except that (a) the  purchase  of our common  stock shall not at the
time of delivery be prohibited  under the laws of the  jurisdiction to which the
purchaser  is  subject  and  (b) if our  common  stock  is  also  being  sold to
underwriters,  we shall have sold to the  underwriters our common stock not sold
for delayed delivery. The underwriters,  dealers and other persons will not have
any  responsibility in respect to the validity or performance of contracts.  The
prospectus  supplement relating to contracts will set forth the price to be paid
for our  common  stock  pursuant  to  contracts,  the  commissions  payable  for
solicitation  of  contracts  and the date or dates in the future for delivery of
our common stock pursuant to contracts.

The  anticipated  date of delivery of our common  stock will be set forth in the
applicable prospectus supplement relating to each offer.

The 2,000,000 shares of common stock  previously  issued in the name of Advanced
Magnetics,  Inc., the 2,179,158 shares of common stock previously  issued in the
name of Acqua  Wellington  North American  Equities Fund, Ltd. and the 1,820,000
shares  of  common  stock to be  issued  in the name of the  State of  Wisconsin
Investment  Board  hereunder  have  been,  and any  shares  sold  pursuant  to a
prospectus supplement are expected to be, listed on the Nasdaq National Market.

We may grant  underwriters  who  participate in the  distribution  of our common
stock an option to purchase additional common stock to cover over-allotments, if
any.

LEGAL MATTERS

The validity of the shares offered hereby has been passed upon for us by Dechert
Price & Rhoads, Princeton, New Jersey.

EXPERTS

Our  financial  statements  contained in our Annual  Report on Form 10-K for the
year ended December 31, 1999, and  incorporated  by reference in this prospectus
and  elsewhere  in the  registration  statement,  have  been  audited  by Arthur
Andersen LLP, independent public accountants,  as indicated in their report with
respect thereto,  and are incorporated  herein by reference in reliance upon the
authority of said firm as experts in giving said reports.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational  requirements of the Securities Exchange Act
of 1934.  Accordingly,  we file annual,  quarterly  and special  reports,  proxy
statements and other  information  with the Securities and Exchange  Commission.
You may read  and  copy any  document  that we have  filed at the  SEC's  public
reference  room  at  Room  1024,   Judiciary  Plaza,  450  Fifth  Street,  N.W.,
Washington,  D.C.  20549.  Please  call the SEC at  1-800-SEC-0330  for  further
information  on the public  reference  room.  You can  obtain  copies of our SEC
filings at  prescribed  rates by writing to the SEC.  Our SEC  filings  are also
available to you free of charge at the SEC's web site at http: //www.sec.gov.

Shares of our common stock are traded on the Nasdaq National  Market.  Documents
we have filed can be  inspected at the offices of the  National  Association  of
Securities Dealers, Inc., Reports Section, 1735 K Street, N.W., Washington, D.C.
20006.

                                       19




This  prospectus is a part of a  Registration  Statement on Form S-3 filed by us
with the SEC under the Securities Act of 1933.  This prospectus does not contain
all of the information contained in the registration  statement,  parts of which
are omitted in accordance with the rules and regulations of the SEC. For further
information  with  respect  to us and the  shares of our  common  stock  offered
hereby, please refer to the registration  statement.  The registration statement
may be inspected at the public reference facilities maintained by the SEC at the
addresses provided above. Statements in this prospectus about any document filed
as an exhibit are not  necessarily  complete and, in each  instance,  you should
refer  to the  copy of the  document  filed  with the  SEC.  Each  statement  is
qualified in its entirety by such reference.

INFORMATION INCORPORATED BY REFERENCE

The SEC allows us to  incorporate  by reference the  information  filed with it,
which means that we can disclose  important  information to you by referring you
to those documents.  The information  incorporated by reference is considered to
be part of this  prospectus,  and information  that we have filed later with the
SEC will  automatically  update  and  supersede  previously  filed  information,
including information contained in this prospectus.

We incorporate by reference the documents listed below and any future filings we
will make with the SEC under Sections 13(a),  13(c), 14 or 15(d) of the Exchange
Act until this offering has been completed:

o    Annual  Report on Form 10-K for the fiscal  year ended  December  31,  1999
     (File No. 333-02015);

o    Quarterly  Report on Form 10-Q for the  quarter  ended March 31, 2000 (File
     No. 333-02015);

o    Schedule 14A and Proxy Statement of the Company filed April 18, 2000;

o    Quarterly Report on Form 10-Q for the quarter ended June 30, 2000;

o    Current Report on Form 8-K filed July 14, 2000;

o    Current Report on Form 8-K filed September 7, 2000;

o    Registration Statement filed pursuant to Rule 424(b)(2) filed September 29,
     2000;

o    Current Report on Form 8-K filed October 5, 2000;

o    Current Report on Form 8-K filed October 12, 2000;

o    Registration Statement on Form S-8 filed October 18, 2000;

o    Registration Statement on Form S-8 filed October 23, 2000;

o    Quarterly Report on Form 10-Q for the quarter ended September 30, 2000;

o    Registration  Statement  filed pursuant to Rule 424(b)(2) filed February 5,
     2001;

o    Current Report on Form 8-K filed on February 6, 2001;

o    Annual Report on Form 10-K for the fiscal year ended December 31, 2000;

o    Registration Statement on Form S-8 filed April 6, 2001;

o    Registration Statement on Form S-8 filed April 27, 2001;

o    Schedule 14A and Proxy Statement of the Company filed April 30, 2001;

o    Quarterly Report on Form 10-Q for the quarter ended March 31, 2001; and

o    the description of our common stock contained in the registration statement
     on Form 8-A (File No. 000-14879), as amended.

                                       20




Any statement  contained in a document that is incorporated by reference will be
modified or superseded for all purposes to the extent that a statement contained
in this prospectus (or in any other document that is subsequently filed with the
SEC and  incorporated  by  reference)  modifies or is contrary to that  previous
statement.  Any statement so modified or superseded will not be deemed a part of
this prospectus except as so modified or superseded.

You may request a free copy of these  documents by writing  Cytogen  Corporation
Corporate  Communications,  600 College Road East CN 5308, Princeton, New Jersey
08540-5308, or by calling us at (609) 750-8224.

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