Gilead Sciences Announces Acceptance Of Late Breaker Abstract At Upcoming Scientific Conference

Preliminary Data from Phase II Study of Anti-HIV Agent

Foster City, CA -- September 13, 1999

Gilead Sciences (Nasdaq: GILD) today announced that preliminary Phase II clinical data for its investigational anti-HIV agent, tenofovir disoproxil fumarate (tenofovir DF), will be presented in a late breaker presentation at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) taking place in San Francisco, CA, from September 26-29, 1999.

Principal clinical investigator Robert Schooley, MD, Professor and Division Head, Infectious Diseases, University of Colorado, will present preliminary 24-week safety and efficacy data on 189 patients from Study 902 of tenofovir DF on Monday, September 27 at 12:48 p.m. in Late Breaker Session #93.1.

Gilead products and investigational compounds will be the subject of 18 additional posters or presentations during the ICAAC conference and are detailed in the accompanying summary. Copies of the abstracts may be obtained from the ICAAC Web site or by contacting Gilead’s Corporate Communications department at 650-522-5402. Late breaker abstracts will be made available to conference participants upon registration at the meeting.

Gilead Sciences, headquartered in Foster City, CA, is an independent biopharmaceutical company that seeks to provide accelerated solutions for patients and the people who care for them. The Company discovers, develops, manufactures and commercializes proprietary therapeutics for challenging infectious diseases (viral, fungal and bacterial infections) and cancer. Gilead maintains research, development or manufacturing facilities in Foster City, CA, Boulder, CO, San Dimas, CA, and Cambridge, UK, and sales and marketing organizations in the United States, Europe and Australia. Gilead common stock is traded on The Nasdaq Stock Market under the symbol GILD.