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, 2003

                                  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-______)



SERONO                                                     (OSI) PHARMACEUTICALS



Media Release


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

      SERONO AND OSI PHARMACEUTICALS ANNOUNCE AGREEMENT FOR OSI TO MARKET
                            NOVANTRONE(R) IN ONCOLOGY


GENEVA,  SWITZERLAND  AND  MELVILLE,  NEW  YORK-  MARCH  12, 2003 -- Serono S.A.
(virt-x:  SEO  and  NYSE:  SRA)  and  OSI  Pharmaceuticals,  Inc. (NASDAQ: OSIP)
announced  today  that  they  have  entered  into an agreement by which OSI will
market  and  promote  the  drug  Novantrone(R)  (mitoxantrone  concentrate  for
injection)  for  the  approved  oncology  indications  in the United States.  In
consideration  for  these  exclusive  rights,  OSI  will pay Serono initial fees
totaling  $55  million  plus  maintenance  fees in return for commissions on net
sales  in  oncology.  To  support Novantrone(R), OSI intends to build commercial
operations  which  will  include  a  sales force and an associated marketing and
sales  management  infrastructure.

Novantrone(R)  is  approved  by  the  U.S.  Food and Drug Administration for the
treatment  of  acute nonlymphocytic leukemia (ANLL), which includes myelogenous,
promyelocytic,  monocytic  and erythroid acute leukemias, and the relief of pain
associated  with advanced hormone-refractory prostate cancer (HRPC). The drug is
also approved for certain advanced forms of multiple sclerosis (MS). Serono will
continue  to  be  responsible  for  the  marketing  of  the  multiple  sclerosis
indication  for  Novantrone(R) and book all U.S. sales in all indications. Total
sales  of Novantrone(R) in 2002, were approximately $80 million. Serono acquired
from Amgen the U.S. rights to Novantrone(R) for both MS and oncology in December
2002.

"Gaining  access  to  a  high-quality, marketed oncology product to both build a
revenue  base  and  allow  us  to  seed a commercial organization has been a key
corporate  goal  over  the  last  two years," stated Colin Goddard, Ph.D., Chief
Executive  Officer  of  OSI  Pharmaceuticals.  "We  see  Novantrone(R) as a well
established  therapeutic product in oncology of about the right size that became
available  at  the  right  time  and  have  moved  aggressively  to  secure this
opportunity.  We  believe  our new relationship with Serono represents a win-win
for  both  parties.  Further,  we  believe  this deal, coupled with our recently
announced  intention  to  acquire  Cell Pathways' pro-apoptotic pipeline and the
marketed  oncology-care  product  Gelclair(TM), represent major steps forward in
continuing  to  build  a  high  quality  oncology  organization."

"We have found an excellent partner in OSI, who have a significant commitment to
developing  a  commercial  presence  in  the  field  of  oncology," said Ernesto
Bertarelli,  Serono's Chief Executive Officer. "This agreement enables Serono to
focus  on  Novatrone(R)  in  our  specialist  area  of multiple sclerosis, while
ensuring  that  the  product  continues  to  be  well  supported in its oncology
indications."

Novantrone(R)  (mitoxantrone  for  injection  concentrate)  is  a  synthetic
antineoplastic  anthracenedione  used intravenously as an anti-cancer agent. The
product  was  approved by the FDA in 1987 for ANLL and in 1996 for the relief of
pain associated with HRPC. It was registered for MS indications in October 2000.
It  is a DNA-reactive agent that intercalates into DNA through hydrogen bonding,
causing crosslinks and strand breaks. Novantrone(R) also interferes with RNA and
is  a  potent inhibitor of topoisomerase II, an enzyme responsible for uncoiling
and  repairing  damaged  DNA.



ABOUT SERONO
Serono  is  a  global  biotechnology  leader.  The  Company  has six recombinant
products  on  the  market,  Rebif(R),  Gonal-F(R),  Luveris(R),  Ovidrel(R)/
Ovitrelle(R), Serostim(R) and Saizen(R) (Luveris(R) is not approved in the USA).
In  addition to being the world leader in reproductive health, Serono has strong
market positions in neurology, metabolism and growth. Serono's research programs
are  focused  on  growing  these  businesses and on establishing new therapeutic
areas. Currently, there are over 30 projects in development.

In  2002,  Serono  achieved  worldwide  revenues of US $1.546 billion, and a net
income  of  US  $321 million, making it the third largest biotech company in the
world.  Serono  operates  in 45 countries, and its products are sold in over 100
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).

ABOUT OSI
OSI  Pharmaceuticals,  Inc.  is  a  leading biotechnology company focused on the
discovery,  development  and  commercialization of high-quality, next-generation
oncology  products  that  both extend and improve the quality-of-life for cancer
patients worldwide. OSI has a balanced pipeline of oncology drug candidates that
includes  both  next-generation  cytotoxic  agents  and  novel  mechanism-based,
gene-targeted  therapeutics.  OSI's  most  advanced  drug candidate, Tarceva(TM)
(erlotinib  HCl),  a  small-molecule inhibitor of the EGFR gene, is currently in
Phase III clinical trials for lung and pancreatic cancers.


This  news  release  contains  forward-looking  statements. These statements are
subject  to  known  and  unknown  risks  and uncertainties that may cause actual
future  experience  and  results  to differ materially from the statements made.
Factors  that might cause such a difference include, among others, the impact of
acquisitions and divestitures on the synergies of OSI's programs, the success of
research and development activities and of pre-clinical development thereof, the
completion  of  clinical  trials,  the FDA review process and other governmental
regulation,  pharmaceutical  collaborators'  ability to successfully develop and
commercialize  drug candidates, competition from other pharmaceutical companies,
product  pricing  and  third party reimbursement, and other factors described in
OSI  Pharmaceuticals'  filings  with  the  Securities  and  Exchange Commission.


                                       ###
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 May 21 2002. 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.
                                       ###



                                     -more-



FOR MORE INFORMATION, PLEASE CONTACT:

SERONO IN GENEVA, SWITZERLAND:
MEDIA  RELATIONS:                 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: SEOZ.VX / SRA.N
---------------------             Bloomberg: SEO VX / SRA US


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




Contact:   OSI Pharmaceuticals, Inc.        Burns  McClellan (representing OSI)
           Kathy  Galante                   Jonathan Nuggent (investors)
           Director                         Kathy Jones, Ph.D. (media)
           Investor & Public Relations      (212) 213-0006
           (631) 962-2000



                                      -end-



                                   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 12, 2003                     By:   /s/ Allan Shaw
                                         -------------------
                                         Name:   Allan Shaw
                                         Title:  Chief Financial Officer