Gilead Sciences Announces Changes to Senior Management Team

Foster City, CA -- December 6, 1999

Gilead Sciences (Nasdaq: GILD) announced today that Howard S. Jaffe, M.D., Senior Vice President of Drug Development, will become a part-time employee and will join Gilead’s Scientific Advisory Board effective January 1, 2000. He will resign as an executive officer of the Company. Dr. Jaffe decided to make the transition to advisory status in order to spend more time with his family; he does not plan to participate in a business that is competitive with Gilead.

“Since Howard joined our senior management team in 1991, he has made key contributions to our successes as we evolved into a public company, developed and launched Vistide® and Tamiflu™, and merged with NeXstar,” said John C. Martin, President and Chief Executive Officer. “I look forward to his continuing involvement and counsel on the strategic issues we face over the years to come.”

Dr. Jaffe’s management responsibilities at Gilead will be shared by Norbert Bischofberger, Ph.D., Senior Vice President of Research, and Nicole Onetto, M.D., Vice President of Medical Affairs. Dr. Bischofberger joined Gilead in 1990 and will continue his responsibilities for discovery and preclinical research. Dr. Onetto left Bristol-Myers Squibb in 1997 to join NeXstar Pharmaceuticals, Inc. and joined Gilead upon the acquisition of NeXstar in July 1999. Dr. Onetto is based in the Company’s Boulder, CO office.

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.