COMUNICADO DE SERONO INTERNATIONAL S.A.

Serono Launches Rebif.net Website

New Website Offers In-Depth Information on Rebif(R) and on Management of Multiple Sclerosis as Well as an Up-To-Date News Service

GENEVA (SWITZERLAND), 22 (PRNewswire)

Serono (virt-x: SEO and NYSE: SRA), the third largest biotechnology company in the world, announced today the launch of Rebif.net (http://www.rebif.net), a new website for its multiple sclerosis (MS) therapy Rebif(R) (interferon beta-1a). This website offers an authoritative and comprehensive source of information to patients treated with Rebif(R), caregivers, nurses and physicians, as well as other people who might have an interest in MS.[1]

"The Rebif.net website is one more illustration of Serono's commitment to support people treated with Rebif(R) and to serve everyone involved in the treatment and management of multiple sclerosis," said Tony Coombs, Corporate Vice President, Neurology. "The ultimate objective of this comprehensive online resource on multiple sclerosis is to help optimise treatment and management of the disease."

Rebif.net provides in-depth information on Rebif(R) as well as medical information on MS and on its treatment, tips for living with the disease, practical advice on management of MS-related symptoms, and information on Serono's support programs for MS patients. In addition, Rebif.net offers an up-to-date news service with recent developments in the field of MS. Furthermore, Rebif.net gives a comprehensive list of links to MS associations and organisations and other websites that may be helpful for those affected by MS.

Rebif.net allows customised access for patients, physicians and nurses with sections specifically designed for each of these audiences. The launch of Rebif.net announced today will be followed by the launch of Rebif.net local web sites in 28 countries[2] (14 languages) by the end of the year.

About Rebif(R)

Rebif(R) (interferon beta-1a) is a disease-modifying drug used to treat relapsing forms of multiple sclerosis and is similar to the interferon beta protein produced by the human body. Interferon helps modulate the body's immune system, fight disease and reduce inflammation.

Rebif(R), which was approved in Europe in 1998 and in the US in 2002, is registered in more than 80 countries worldwide. In the United States, Rebif(R) is co-marketed by Serono, Inc. and Pfizer Inc. Rebif(R) has been proven to reduce MRI lesion activity and area (i), reduce the frequency of relapses, and delay the progression of disability. Rebif(R) is available in a 22 mcg and 44 mcg ready-to-use pre-filled syringe and can be stored at room temperature for up to 30 days if a refrigerator is not available.

Most commonly reported side effects are injection site disorders, flu-like symptoms, elevation of liver enzymes and blood cell abnormalities. Patients, especially those with depression, seizure disorders, or liver problems, should discuss treatment with Rebif(R) with their doctors.

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.

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 US 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 commercialising 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 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).

http://www.serono.com

Notes

[1] This website is not intended for US residents. US residents should consult the Serono, Inc Rebif website at www.rebif.com.

[2] Algeria, Australia, Austria, Belgium, Brazil, Canada, Denmark, Egypt, Estonia, Finland, Germany, Latvia, Lithuania, Morocco, Netherlands, Hungary, Iran, Norway, Poland, Portugal, Saudi Arabia, South Africa, Spain, Sweden, Switzerland, Tunisia, Turkey, United Kingdom

(i) The exact relationship between MRI findings and the clinical status of patients is unknown

Source: Serono International S.A.

Contact: Corporate Media Relations: Tel: +41-22-739-36-00, Fax: +41-22-739-30-85. Corporate Investor Relations: Tel: +41-22-739-36-01, Fax: +41-22-739-30-22. Investor Relations, USA: Tel: +1-781-681-2552, Fax: +1-781-681-2912

(177000)