Gilead Sciences Announces Termination of Genetic Code Blocker Research Collaboration with Glaxo Wellcome

Foster City, CA -- June 26, 1998

Gilead Sciences, Inc. (Nasdaq: GILD) announced today the termination of its collaborative research agreement with Glaxo Wellcome Inc. for the research and development of genetic code blockers, also known as antisense. Gilead and Glaxo Wellcome, then Glaxo Inc., first entered into a collaborative agreement for the development of genetic code blockers in 1990 and have extended the collaboration several times, most recently in 1996.

Genetic code blocker research is designed to identify and develop new pharmaceutical compounds that prevent the production of disease-causing proteins at the genetic level. Under the terms of the agreement, Glaxo Wellcome has funded Gilead's research efforts in this field since the collaboration began in 1990.

"Through our long-standing collaboration, Gilead and Glaxo Wellcome have made a number of important scientific and proprietary discoveries that have advanced the field of antisense," said Norbert Bischofberger, Senior Vice President, Research at Gilead. "These advances include the identification of compounds with increased cell permeation and increased potency and have moved this program closer to the goal of broadly applicable pharmaceuticals."

At this time, each company retains rights to the technology jointly developed as part of the collaboration and to scientific advancements each company made on its own. Gilead is now free to license its interest in the code blocker technology to another company. Gilead has initiated discussions with other companies regarding the code blocker technology, but there can be no assurances that a definitive agreement can be reached.

Gilead Sciences is an independent biopharmaceutical company that seeks to provide accelerated solutions for patients and the people who care for them. The Company discovers, develops and commercializes proprietary therapeutics for important viral diseases, including a currently marketed product for the treatment of CMV retinitis, a sight-threatening viral infection in patients with AIDS. In addition, the Company is developing products to treat diseases caused by HIV, hepatitis B virus and influenza virus. Gilead common stock is traded on The Nasdaq Stock Market under the symbol GILD.

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