Gilead Sciences Submits Marketing Authorisation Application to European Regulatory Authorities for Tenofovir DF for the Treatment of HIV Infection

Foster City, CA -- May 4, 2001

Gilead Sciences, Inc. (Nasdaq: GILD) today announced that it has submitted a Marketing Authorisation Application (MAA) to the European Agency for the Evaluation of Medicinal Products (EMEA) seeking approval of tenofovir disoproxil fumarate (tenofovir DF) for the treatment of human immunodeficiency virus (HIV) infection. Gilead submitted a New Drug Application (NDA) for tenofovir DF for the treatment of HIV infection to the U.S. Food and Drug Administration (FDA) on May 1, 2001.

Tenofovir DF is dosed as a single 300 mg tablet taken once daily and works by blocking reverse transcriptase, an enzyme crucial to the replication of HIV. As an investigational compound, tenofovir DF has not yet been determined safe or efficacious in humans for its ultimate intended use.

The MAA will be reviewed under the centralized licensing procedure, which, when finalized, provides one marketing authorization valid in all 15 member states of the European Community. Review of the application will be coordinated by the EMEA. The French authorities will act as rapporteur and the Spanish authorities will act as co-rapporteur for the procedure.

"This European regulatory filing represents another important step toward our goal of providing tenofovir DF to patients and physicians in an accelerated manner," said John C. Martin, Ph.D., President and Chief Executive Officer, Gilead Sciences. "The submission of the NDA and MAA within three days of each other marks an impressive accomplishment and is reflective of the hard work of the Gilead team."

"There are increasing needs across Europe for treatments to combat HIV infection, particularly for individuals who have failed other therapy. Based on data from clinical studies of tenofovir DF, this compound holds the potential to address the needs of patients at various stages of their HIV disease," said Brian Gazzard, M.D., Chelsea and Westminster Hospital and Clinical Research Director, Imperial College, London.

Early Access Program Initiated
In January, Gilead announced the initiation of an expanded access program to provide tenofovir DF to people with advanced HIV infection. Regulatory review has been concluded and programs are open for registration in the United States, France, Spain and the United Kingdom. Gilead expects to initiate early access programs in Germany, Italy, Canada and other countries as local regulatory approvals are obtained.

For more information regarding the tenofovir DF early access program or to request registration materials, physicians in the United States may call 1-800-GILEAD-5 and those within Europe may call 33-1-44-90-34-46.

Gilead Sciences
Gilead Sciences, Inc., headquartered in Foster City, CA, USA, is an independent biopharmaceutical company that seeks to provide accelerated solutions for patients and the people who care for them. Gilead discovers, develops, manufactures and commercializes proprietary therapeutics for challenging infectious diseases (viral, fungal and bacterial infections) and cancer. Gilead maintains research facilities in Foster City, CA; Boulder, CO; San Dimas, CA; Cambridge, UK; and Dublin, Ireland; and sales and marketing organizations in the United States, Europe and Australia.

This press release includes forward-looking statements, within the meaning of the Private Securities Litigation Reform Act of 1995, that are subject to risks, uncertainties and other factors that could cause actual results to differ materially from those referred to in the forward-looking statements. Such risks and uncertainties include risks related to regulatory approval of tenofovir DF. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in the Gilead Annual Report on Form 10-K for the year ended December 31, 2000 and in Gilead's Quarterly Reports on Form 10-Q, all of which are on file with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead and Gilead assumes no obligation to update any such forward-looking statements.

# # #

For more information on Gilead Sciences, please visit the company's Web site at www.gilead.com or call the Gilead Corporate Communications Department at 1-800-GILEAD-5 (1-800-445-3235).