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 September, 2004

                                   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-     )
                                                 -----



ZYMOGENETICS                                                              SERONO


Media Release


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




    ZYMOGENETICS AND SERONO ESTABLISH BROAD STRATEGIC RESEARCH, DEVELOPMENT AND
                           COMMERCIALIZATION ALLIANCE

          SERONO AND ZYMOGENETICS TO COLLABORATE IN THE DEVELOPMENT OF
                     NOVEL PROTEIN AND ANTIBODY THERAPEUTICS



SEATTLE  (UNITED  STATES)  AND  GENEVA  (SWITZERLAND),  SEPTEMBER  8,  2004  -
ZymoGenetics,  Inc.  (Nasdaq: ZGEN) and Serono (virt-x: SEO and NYSE: SRA) today
announced  their  intent  to enter into a broad partnership to research, develop
and  commercialize  novel protein and antibody therapeutics based on discoveries
made  by  ZymoGenetics.

As part of this alliance:

     -    Serono  will  gain  access to a large portfolio of ZymoGenetics' genes
          and  proteins  for  in-house  evaluation  and screening, and rights to
          license  such  proteins  over  the  next  five  years.

     -    Serono will also have rights over the next five years to license up to
          twelve  products  arising  from  ZymoGenetics'  internal core research
          projects.  ZymoGenetics  will  have  an  option  to  co-develop  and
          co-commercialize  in  the  U.S. any products selected by Serono. Until
          November 2006, Serono's rights to exclusively license proteins outside
          the  U.S.  will  be  subordinate  to  certain existing options of Novo
          Nordisk  under  a  separate  agreement.

     -    ZymoGenetics  will  license  to  Serono  exclusive worldwide rights to
          develop  and  commercialize products based on Fibroblast Growth Factor
          18 (FGF-18) and the Interleukin 22 Receptor (IL-22R). In addition, the
          companies  will  co-develop  Interleukin  31  (IL-31).


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Expected payments to ZymoGenetics include:

     -    A  payment  of  $20  million  in  exchange  for  the rights to license
          proteins  over  the  next  five  years.

     -    The  purchase  of  $50  million  of  ZymoGenetics'  common  stock.

     -    An equal share of profits from the co-commercialization of products in
          the  U.S.  for  which  ZymoGenetics  has  co-funded  development.

     -    For  every  protein  exclusively  licensed  or co-developed by Serono,
          up-front  fees  as  well  as  potential  milestone payments related to
          development  progress,  regulatory  submissions  and  approvals.

     -    Royalty  payments on product sales outside the U.S. and, to the extent
          ZymoGenetics  elects  not  to co-develop products, on product sales in
          the  U.S.

The  terms  of this agreement are subject to review by the United States Federal
Trade  Commission  and Department of Justice, under the provisions of Section 7A
of  the  Clayton  Act,  15  U.S.C.  Sec.  18a, as added by the Hart-Scott-Rodino
Antitrust  Improvements  Act  of  1976.

"We  are enthusiastic about building this alliance with Serono," said Bruce L.A.
Carter,  Ph.D.,  President  and  Chief  Executive  Officer  of  ZymoGenetics.
"Maximizing  the  value  of  our  broad pipeline requires the effort of a proven
research,  development  and  commercial  enterprise.  Serono  has  not  only
demonstrated  its  strengths  in  these  areas, but also has proven an effective
partner  in  our  collaborative  development  of TACI-Ig. The combination of our
resources  should work to create value for both companies over the years ahead."

"We  are  very  pleased to expand our fruitful collaboration with ZymoGenetics",
said  Ernesto  Bertarelli,  Chief  Executive  Officer  of  Serono. "By combining
ZymoGenetics'  strong  pipeline  of  therapeutic  protein  candidates  with  our
research  and  development  capabilities, we are well positioned to bring to the
market  further  innovative  treatments  for medical conditions with significant
unmet  needs".

Three  license  agreements  for FGF-18, IL-22R and IL-31 will be entered into as
part  of  this  alliance. Serono will have worldwide exclusive rights for FGF-18
and  IL-22R,  which  may  be  useful  for  repairing  cartilage  damaged  by
osteoarthritis  or  physical  injury,  and psoriasis, respectively. ZymoGenetics
will  retain  co-development  and  co-commercialization  rights  in the U.S. for
IL-31, which could be useful in treating inflammatory conditions such as asthma,
psoriasis and inflammatory bowel disease. In addition to the $20 million payment
mentioned  above, ZymoGenetics will receive initial license fees totaling $11.25
million  related  to  these three projects. Total upfront and milestone payments
under  these  licenses  could  exceed  $100  million.

Serono reiterates its guidance for 2004 with an increase in total revenues of at
least  12%  and  an  increase in net income of at least 20% in local currencies.


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ZymoGenetics  will conduct a conference call/webcast in conjunction with today's
release  at  8:30  A.M.  ET  on  Wednesday,  September 8, 2004. The webcast will
include  a  slide  presentation.  Members  of  the news media, investors and the
general public are invited to access a live broadcast of the conference call via
the  ZymoGenetics  website  at  HTTP://WWW.ZYMOGENETICS.COM/IR/EVENTS.PHP  or
                               ------------------------------------------
through  www.vcall.com. The event will be archived. The telephone replay will be
         -------------
available until 11:59 PM Pacific Time on September 14, 2004. The webcast will be
available  for  replay  until  11:59  PM  Pacific  Time  on  October  7,  2004.

Phone numbers and access codes for the conference call are as follows:

Live Call- Domestic: 800-370-0740        International: 973-409-9259
An operator will answer calls for the live event.

Archived Call- Domestic 877-519-4471     International: 973-341-3080

Replay Passcodes (required for playback):
Account #: 1628
Conference ID #: 5131574

About FGF-18

Fibroblast  growth  factor-18  (FGF-18)  plays an important role during skeletal
development  and appears to be a trophic factor for chondrocytes, the cells that
produce cartilage of the joint surfaces, in mammals. ZymoGenetics has previously
shown  that  FGF-18  and  the  genes  for  two of its receptors are expressed by
chondrocytes  in  adult  human  articular  cartilage.  Addition of FGF-18 to the
culture  medium  of  these  cells  increased  both their proliferation and their
production of extracellular matrix. Similar changes in chondrocyte proliferation
and  matrix  deposition  were  observed  at a number of sites following local or
systemic  delivery  of  FGF-18. These data suggest that FGF-18 may be useful for
healing  cartilage  damaged  by  injury  or  disease.


About IL-22R

The  IL-10  family  cytokines  IL-20 and IL-22 are pro-inflammatory and each can
signal via the receptor subunit IL-22R alpha. Considerable evidence supports the
inflammatory  roles  of  IL-20  and  IL-22 in psoriasis including their elevated
expression in psoriatic lesions, transgenic mice phenotypes, genetic association
data and animal pharmacology. Expression of the receptor subunit IL-22R alpha is
also  elevated  in  psoriatic lesions. Current work is directed towards choosing
the  most suitable antagonist for evaluation in the treatment of psoriasis. Such
antagonists  may also have use in other instances of impaired epithelial barrier
function,  such  as  in  inflammatory  bowel  disease.


About IL-31

ZymoGenetics  researchers  discovered Interleukin 31 (IL-31) using the Company's
genomics-based  discovery  platform.  Current  in vitro and in vivo data suggest
that  IL-31 may affect cellular infiltration and inflammation. Analysis of IL-31
and  IL-31  receptor  levels  in  human and murine disease tissues suggests that
expression  of  IL-31,  and/or  its  receptor, is significantly increased in the
settings  of  inflammatory bowel disease, asthma and psoriasis. Further evidence
suggests  a  potential  role of IL-31 in the development of atopic dermatitis. A
paper by ZymoGenetics scientists published in the July 2004 issue of the journal
Nature  Immunology  characterizes  IL-31,  illustrates  the hypothesized role of
IL-31  in atopic dermatitis and respiratory disease, and suggests directions for
future  investigation  of  this  cytokine  and  its  role  in  human  diseases.

                                      ###


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ABOUT  ZYMOGENETICS
ZymoGenetics  is  a  biopharmaceutical  company  focused  on  the  discovery,
development  and commercialization of therapeutic proteins for the prevention or
treatment  of  human  diseases.  The Company is developing a diverse pipeline of
potential  proprietary  product  candidates  that  are  moving  into and through
clinical  development.  These  span  a wide array of clinical opportunities that
include  bleeding,  autoimmune  diseases  and  cancer.  ZymoGenetics  intends to
commercialize  these  product  candidates  through  internal  development,
collaborations  with  partners,  and out-licensing of patents from its extensive
patent  portfolio.  For  further  information,  visit  www.zymogenetics.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) (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 and has
recently entered the psoriasis area. The Company's research programs are focused
on  growing  these  businesses  and  on  establishing  new  therapeutic  areas.
Currently,  there  are  approximately  30  ongoing  development  projects.

In  2003,  Serono  achieved  worldwide revenues of US$2,018.6 million, and a net
income  of  US$390.0 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).

BACKGROUND  MATERIAL
For  free  B-roll, video and other content about Serono, please visit the Serono
Media Center www.thenewsmarket.com/Serono. You can download print-quality images
             ----------------------------
and  receive  broadcast-standard  video  digitally  or  by  tape from this site.
Registration  and  video  is  free  to  the  media.

ZymoGenetics  forward-looking  statements
This  press  release contains "forward-looking statements" within the meaning of
the  Private  Securities  Litigation  Reform Act of 1995.  These forward-looking
statements are based on the current intent and expectations of the management of
ZymoGenetics.  These  statements  are  not  guarantees of future performance and
involve  risks  and  uncertainties  that are difficult to predict. ZymoGenetics'
actual  results  and the timing and outcome of events may differ materially from
those expressed in or implied by the forward-looking statements because of risks
associated  with  our  unproven  discovery  strategy,  preclinical  and clinical
development,  regulatory  oversight, intellectual property claims and litigation
and other risks detailed in ZymoGenetics' public filings with the Securities and
Exchange  Commission, including ZymoGenetics' Annual Report on Form 10-K for the
year ended December 31, 2003. Except as required by law, ZymoGenetics undertakes
no  obligation  to  update any forward-looking or other statements in this press
release,  whether  as  a  result of new information, future events or otherwise.


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 25, 2004. 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.

                                      ###


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FOR MORE INFORMATION, PLEASE CONTACT:

ZYMOGENETICS

Investor Relations                            Media Relations
------------------                            ---------------
John Calhoun, MD, MBA                         Susan W. Specht, MBA
Director, Corporate Communications            Corporate Communications Manager
& Investor Relations                          (206) 442-6592
(206) 442-6744


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 2486          Tel:  +1 781 681 2552
 Fax:  +1 781 681 2935          Fax:  +1 781 681 2912
 http://www.seronousa.com
 --------------------------


                                                                             5/5

                                   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)



September 8, 2004                  By:   /s/ Francois Naef
                                         -------------------------
                                   Name:  Francois Naef
                                   Title: Secretary