SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    ________

                                    FORM 6-K

                        REPORT OF FOREIGN PRIVATE ISSUER
                      PURSUANT TO RULE 13a-16 OR 15d-16 OF
                       THE SECURITIES EXCHANGE ACT OF 1934

                          For the month of August, 2005

                                   Serono S.A.
                ------------------------------------------------
                               (Registrant's Name)

                            15 bis, Chemin des Mines
                                 Case Postale 54
                                CH-1211 Geneva 20
                                   Switzerland
                    ----------------------------------------
                    (Address of Principal Executive Offices)

                                     1-15096
                ------------------------------------------------
                              (Commission File No.)

     (Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.)

     Form 20-F   X   Form 40-F
               -----           -----

     (Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(1).)
                                                       -----

     (Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(7).)
                                                       -----

     (Indicate by check mark whether the registrant by furnishing the
information contained in this form is also thereby furnishing the information to
the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of
1934.)

     Yes       No   X
         -----    -----

     (If "Yes" is marked, indicate below the file number assigned to the
registrant in connection with Rule 12g3-2(b): 82-     )
                                                 -----



GENMAB                                                                    SERONO


MEDIA RELEASE


FOR IMMEDIATE RELEASE
---------------------


   SERONO AND GENMAB ANNOUNCE GLOBAL DEVELOPMENT AND COMMERCIALIZATION AGREEMENT
                                  FOR HUMAX-CD4

   HuMax-CD4 currently in Phase III Clinical Trial for Cutaneous T-Cell Lymphoma
          and Phase II Clinical Trial for Non-Cutaneous T-Cell Lymphoma

GENEVA,  SWITZERLAND AND COPENHAGEN, DENMARK - AUGUST 18, 2005 -
Serono  (virt-x: SEO and NYSE: SRA) and Genmab A/S (CSE: GEN) announced today an
agreement  under  which  Genmab has granted Serono exclusive worldwide rights to
develop  and  commercialize  Genmab's  HuMax-CD4.  HuMax-CD4  is  a  fully human
monoclonal  antibody  in  development  for  the  treatment  of  cutaneous  and
non-cutaneous  T-cell  lymphomas.  It  is currently being evaluated in a pivotal
Phase  III clinical trial for cutaneous T-cell lymphoma (CTCL) under the US Food
and Drug Administration's Special Protocol Assessment process and has Fast Track
designation  from  the  FDA. HuMax-CD4 is also being studied in a Phase II trial
for non-cutaneous T-cell lymphoma (NCTCL). HuMax-CD4 is directed against the CD4
antigen  and  causes  depletion  of  certain  T-cells through antibody-dependent
cellular  cytotoxicity.

Under  the  terms  of the agreement, Genmab will receive a license fee of USD 20
million,  and  Serono  will  make  a  USD 50 million investment in Genmab common
stock,  at  a  premium  to  the  market  price. Genmab may receive up to USD 215
million  in  total  payments,  including  the  initial  license  fee  and equity
purchase,  milestone  payments  for  regulatory  submissions  and  approvals  of
HuMax-CD4  in  CTCL and NCTCL in the US, Europe and Japan, and payments based on
the  achievement of certain sales milestones. Genmab will be entitled to receive
royalties  on  global  sales  of  HuMax-CD4.  Serono will be responsible for all
future  development  costs  for  HuMax-CD4  and  for future manufacturing of the
product.  Genmab  will  continue  to  conduct  the  ongoing  clinical  trials as
described  above.

"Serono's  proficiency  in  bringing biotechnology products to market as well as
their established presence in highly specialized dermatology clinics, which play
a  significant role in the diagnosis and treatment of CTCL, makes the company an
excellent  strategic  partner,"  said  Lisa  N. Drakeman, Ph.D., Chief Executive
Officer  of  Genmab.

"We  are  committed  to building a strong oncology pipeline through partnerships
with  leading  companies such as Genmab, and through our own internal research,"
said  Ernesto  Bertarelli,  Chief  Executive Officer of Serono. "HuMax-CD4 is an
important  addition  to  Serono's oncology portfolio, which now consists of four
different  clinical-stage  products  being  investigated across a broad range of
indications."


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Simultaneously  with this release, Genmab will publish a separate stock exchange
release  containing more information regarding the placement of Genmab shares to
Serono,  which  is  made  in  direct  connection with the Global Development and
Commercialization  Agreement  regarding  HuMax-CD4.


ABOUT  CTCL  AND  NCTCL
-----------------------
Cutaneous  T-cell  lymphomas  (CTCL)  are  a group of lymphomas characterized by
abnormal accumulation of malignant T-cells in the skin, potentially resulting in
the  development  of  rashes,  plaques and tumors. The most common types of CTCL
include  mycosis  fungoides  (MF)  and  Sezary  syndrome (SS).  CTCL result from
errors  in  the  production  of T-lymphocytes or transformation of T-lymphocytes
into  malignant  cells.  Abnormal,  uncontrolled  growth  and  multiplication of
malignant  T-lymphocytes result in accumulation of these lymphocytes in the skin
and  may  in some cases spread and affect the lymph nodes and other body tissues
and  organs,  resulting  in  life-threatening  complications.

Non-cutaneous  T-cell lymphomas (NCTCL) are defined by highly malignant disease,
which  has  localized  to  the  lymph  nodes  even  at  the  earliest  stage  of
presentation,  and  include angioimmunoblastic T-cell lymphoma, anaplastic large
cell  lymphoma  (ALCL)  and  unspecified  peripheral  T-cell  lymphoma. NCTCL is
characterized  by  aggressive  progression  with  average  survival  time  of
approximately  two  years.


ABOUT  HUMAX-CD4  (ZANOLIMUMAB)
-------------------------------
HuMax-CD4  is a human monoclonal antibody currently in Phase III development for
cutaneous  T-cell  lymphoma  (CTCL)  and  in  Phase  II for non-cutaneous T-cell
lymphoma. These types of lymphomas express the CD4 receptor, which is the target
of  HuMax-CD4.  In  April  2005,  Genmab  and  the  United  States Food and Drug
Administration  (FDA)  reached  an  agreement on the design of its pivotal study
protocol  for  HuMax-CD4  to  treat  CTCL  under the Special Protocol Assessment
process  (SPA).  The  pivotal study will include patients with mycosis fungoides
(MF)  who are refractory to or intolerant of Targretin(R) and one other standard
therapy,  and  will  treat  a  total  of  88  patients.

In  March 2004, Genmab announced that HuMax-CD4 had been designated a Fast Track
Product  by  the  US Food and Drug Administration (FDA). This designation covers
patients  with  CTCL  for  whom no available therapy exists, i.e. have failed at
least  two  systemic  treatment  regimens. HuMax-CD4 for the treatment of MF has
also  been  granted  Orphan  Drug  status  in  the  US  and  Europe.


                                       ###

GENMAB FORWARD-LOOKING STATEMENTS
This  press  release  contains  forward-looking statements. The words "believe",
"expect",  "anticipate",  "intend"  and  "plan" and similar expressions identify
forward  looking statements. Actual results or performance may differ materially
from  any future results or performance expressed or implied by such statements.
The  important  factors  that  could  cause our actual results or performance to
differ materially include, among others, risks associated with product discovery
and  development,  uncertainties  related to the outcome and conduct of clinical
trials  including  unforeseen  safety  issues,  uncertainties related to product
manufacturing,  the  lack of market acceptance of our products, our inability to
manage  growth, the competitive environment in relation to our business area and
markets,  our  inability to attract and retain suitably qualified personnel, the
unenforceability  or  lack  of protection of our patents and proprietary rights,
our  relationships  with  affiliated  entities,  changes  and  developments  in
technology  which may render our products obsolete, and other factors. Genmab is
not under an obligation to up-date statements regarding the future following the
publication  of  this  release;  nor  to  confirm such statements in relation to
actual  results,  unless  this  is  required  by  law.

                                       ###


                                                                             2/3

SERONO  FORWARD-LOOKING  STATEMENTS
Some  of  the  statements  in  this  press  release  are  forward  looking. Such
statements  are inherently subject to known and unknown risks, uncertainties and
other  factors  that  may  cause  actual results, performance or achievements of
Serono  S.A.  and  affiliates  to be materially different from those expected or
anticipated  in  the  forward-looking statements. Forward-looking statements are
based on Serono's current expectations and assumptions, which may be affected by
a  number  of  factors, including those discussed in this press release and more
fully  described  in  Serono's  Annual  Report  on Form 20-F filed with the U.S.
Securities  and Exchange Commission on March 16, 2005. These factors include any
failure  or  delay  in  Serono's ability to develop new products, any failure to
receive  anticipated  regulatory  approvals,  any  problems  in  commercializing
current  products  as  a  result of competition or other factors, our ability to
obtain  reimbursement  coverage  for  our  products,  the  outcome of government
investigations and litigation and government regulations limiting our ability to
sell  our  products.  Serono has no responsibility to update the forward-looking
statements  contained  in  this press release to reflect events or circumstances
occurring  after  the  date  of  this  press  release.

                                       ###

ABOUT GENMAB A/S
Genmab A/S is a biotechnology company that creates and develops human antibodies
for  the  treatment  of  life-threatening  and debilitating diseases. Genmab has
numerous products in development to treat cancer, infectious disease, rheumatoid
arthritis  and other inflammatory conditions, and intends to continue assembling
a  broad  portfolio of new therapeutic products. At present, Genmab has multiple
partnerships  to  gain  access  to  disease  targets  and  develop  novel  human
antibodies  including agreements with Roche and Amgen. A broad alliance provides
Genmab  with  access  to  Medarex,  Inc.'s  array  of  proprietary technologies,
including  the  UltiMAb(R)  platform  for  the rapid creation and development of
human  antibodies  to  virtually  any  disease  target. Genmab has operations in
Copenhagen,  Denmark, Utrecht, the Netherlands, and Princeton, New Jersey in the
US.  For  more  information  about  Genmab,  visit  www.genmab.com.
                                                    ---------------

ABOUT SERONO
Serono  is  a  global  biotechnology leader. The Company has eight biotechnology
products,  Rebif(R),  Gonal-f(R),  Luveris(R),  Ovidrel(R)/Ovitrelle(R),
Serostim(R),  Saizen(R),  Zorbtive(TM)  and Raptiva(R). In addition to being the
world  leader  in  reproductive  health,  Serono  has strong market positions in
neurology,  metabolism  and  growth and has recently entered the psoriasis area.
The  Company's  research programs are focused on growing these businesses and on
establishing  new  therapeutic  areas,  including oncology. Currently, there are
approximately  30  ongoing  development  projects.

In  2004,  Serono  achieved  worldwide revenues of US$2,458.1 million, and a net
income  of  US$494.2 million, making it the third largest biotech company in the
world.  Its  products  are  sold  in over 90 countries.  Bearer shares of Serono
S.A.,  the  holding  company,  are  traded  on the virt-x (SEO) and its American
Depositary Shares are traded on the New York Stock Exchange (SRA).

FOR MORE INFORMATION, PLEASE CONTACT:
SERONO

  CORPORATE MEDIA RELATIONS:          CORPORATE INVESTOR RELATIONS:
  Tel:    +41 22 739 36 00            Tel:    +41 22 739 36 01
  Fax:    +41 22 739 30 85            Fax:    +41 22 739 30 22
  http://www.serono.com               Reuters: SEO.VX / SRA.N
  ---------------------               Bloomberg: SEO VX / SRA US


  MEDIA RELATIONS, USA:               INVESTOR RELATIONS, USA:
  Tel:    +1 781 681 2340             Tel:    +1 781 681 2552
  Fax:    +1 781 681 2935             Fax:    +1 781 681 2912
  http://www.seronousa.com
  ------------------------


GENMAB

Helle Husted
Director, Investor Relations
T: +45 33 44 77 30
M: +45 25 27 47 13
E: hth@genmab.com


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                                   SIGNATURES

     Pursuant  to  the  requirements of the Securities Exchange Act of 1934, the
registrant  has  duly  caused  this  report  to  be  signed on its behalf by the
undersigned,  thereunto  duly  authorized.



                                              SERONO S.A.
                                              a Swiss corporation
                                              (Registrant)



August 18, 2005                               By:    /s/ Stuart Grant
                                                     ---------------------------
                                              Name:  Stuart Grant
                                              Title: Chief Financial Officer