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 March, 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-______)



                                                               [GRAPHIC OMITTED]
                                                                          SERONO


MEDIA RELEASE


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


            SERONO ANNOUNCES MAJOR MILESTONE IN IDENTIFYING THE GENES
                         INVOLVED IN MULTIPLE SCLEROSIS

  IDENTIFICATION OF 80 GENES INVOLVED IN THE INFLAMMATORY AND NEURO-DEGENERATIVE
                PATHWAYS OF MS PROVIDE POTENTIAL NEW DRUG TARGETS


GENEVA, SWITZERLAND AND EVRY, FRANCE - MARCH 17, 2005 -
Serono  (virt-x:  SEO  and  NYSE:  SRA), the world's third largest biotechnology
company, announced today that researchers at the Serono Genetics Institute (SGI)
have  achieved a major milestone in identifying and creating a register of genes
involved  in  multiple  sclerosis (MS). For the first time in this disease area,
researchers at the SGI have identified 80 genes involved in the inflammatory and
neuro-degenerative  pathways  of  MS,  based  on a 40% genome scan comparing the
genetic  profile  of  a total of 1,800 people with MS and healthy individuals in
different  populations.

"We  are  excited  about  this  significant  step forward in building a complete
inventory of genes involved in MS, " said Professor Daniel Cohen, Vice-President
and Worldwide Head of Genetics at Serono. "The completion of the MS Whole Genome
Scan in 2006 will lead to a comprehensive catalogue of potential MS drug targets
providing  a  basis  for  the  future  development  of innovative MS therapies."

"We  are  dedicated  to  the  task  of understanding diseases and developing the
treatments  of the future", said Ernesto Bertarelli, CEO of Serono. "Through our
current  marketed  products,  such  as  Rebif(R),  our  research and development
projects  and  the  major  findings  announced today, Serono is underscoring its
commitment  to  improving  the lives of people with MS and will pave the way for
innovative treatments."

The  understanding  of  the  disease  genetics  in MS will enhance Serono's drug
discovery  in  identifying  proteins that can be used either as targets for drug
development  or directly as therapeutics. In addition, the knowledge of genetics
in  MS  provides a basis for better designing safer and more effective drugs and
enabling  physicians  to  address  unmet  needs  and  potentially  better  match
treatments  to  the  individual  patient.


                                                                             1/3

This  large-scale  association  study  was  performed  in  a French, Swedish and
American  population,  including a total of 900 people with MS and an equivalent
number  of healthy individuals.  Researchers at SGI used the Affymetrix GeneChip
technology  to  scan  over  100,000  SNPs  (single  nucleotide polymorphisms) to
identify  the  genes  involved in MS, comparing the genetic profile of cases and
controls.  The next step is to continue this endeavour, applying next generation
GeneChip  technology  to  scan  over 500,000 SNPs and thus complete the MS Whole
Genome  Scan  during  2006.

Serono's  mission  is  to  discover  and  develop  innovative  products to fight
debilitating  diseases, such as MS, and improve the quality of life of patients.
Based  on  the  human genome sequence, this fundamental advance in understanding
the  genetic roots of MS is a major landmark in the development of more targeted
therapies  of  the  future.

                                    - ends -


ABOUT  MULTIPLE  SCLEROSIS
Multiple  sclerosis  is  a chronic, inflammatory condition of the nervous system
and  is  the  most  common, non-traumatic, neurological disease in young adults.
Multiple  sclerosis may affect approximately two million people worldwide. While
symptoms  can  vary,  the  most  common  symptoms  of multiple sclerosis include
blurred vision, numbness or tingling in the limbs and problems with strength and
coordination.  The  relapsing  forms  of multiple sclerosis are the most common.

ABOUT  THE  SERONO  GENETICS  INSTITUTE
Founded  in  1989,  the  company  joined the Serono Group in 2002 and counts 130
people (90% of them working in Research). The expertise acquired all along these
years  makes  the  Serono  Genetics  Institute  a  Center of Excellence in Human
Genetics.  Fully integrated with the global state-of-the-art research facilities
of  Serono,  the  Serono  Genetics  Institute is contributing to create a unique
biotech approach that brings human genetics into all stages of the discovery and
development  process, to increase the quality of Serono's therapeutic molecules.

                                       ###
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,  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.
                                       ###


                                                                             2/3

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:


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
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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)



March 17, 2005                            By:    /s/ Stuart Grant
                                                 -----------------------------
                                          Name:  Stuart Grant
                                          Title: Chief Financial Officer