Marketing Authorisation Application for Ambrisentan Validated by European Medicines Agency

-- Gilead to Receive Milestone Payment from GlaxoSmithKline --

FOSTER CITY, Calif.--(BUSINESS WIRE)--March 23, 2007--Gilead Sciences, Inc. (Nasdaq: GILD) today announced that GlaxoSmithKline's Marketing Authorisation Application (MAA) for ambrisentan for the treatment of pulmonary arterial hypertension (PAH) was validated by the European Medicines Agency (EMEA) following a review by the Committee for Medicinal Products for Human Use (CHMP). Following the validation of an MAA, the dossier is distributed to members of the CHMP for formal review. As a result of this validation, Gilead will receive a milestone payment from GlaxoSmithKline.

About Ambrisentan

Ambrisentan is a non-sulfonamide, propanoic acid-class, endothelin receptor antagonist that is selective for the endothelin type-A (ET(A)) receptor. Activation of the ET(A) receptor by endothelin, a small peptide hormone, leads to vasoconstriction and cell proliferation. PAH is associated with elevated endothelin blood levels. Ambrisentan has been granted orphan drug designation for the treatment of PAH in both the United States and European Union.

The U.S. Food and Drug Administration (FDA) recently accepted for filing and granted a Priority Review for Gilead's New Drug Application (NDA) for marketing approval of ambrisentan (5 mg and 10 mg) for the once-daily treatment of PAH. The FDA has established a target review date, under the Prescription Drug User Fee Act (PDUFA), of June 18, 2007.

As an investigational compound, ambrisentan has not yet been determined safe or efficacious in humans.

GlaxoSmithKline holds rights to commercialize ambrisentan in territories outside of the United States.

About Pulmonary Arterial Hypertension

PAH is a debilitating disease characterized by constriction of the blood vessels in the lungs leading to high pulmonary arterial pressures. These high pressures make it difficult for the heart to pump blood through the lungs to be oxygenated. Patients with PAH suffer from shortness of breath as the heart struggles to pump against these high pressures causing such patients to ultimately die of heart failure. PAH can occur with no known underlying cause, or it can occur secondary to diseases such as connective tissue disease, congenital heart defects, cirrhosis of the liver and HIV infection. PAH afflicts approximately 200,000 patients worldwide.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. The company's mission is to advance the care of patients suffering from life-threatening diseases worldwide. Headquartered in Foster City, California, Gilead has operations in North America, Europe and Australia. For more information on Gilead Sciences, please visit the company's website at www.gilead.com or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

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, including risks related to Gilead's ability to successfully commercialize this product. For example, the EMEA may not approve ambrisentan for the treatment of PAH in the European Union and the FDA may not approve ambrisentan for the treatment of PAH in the United States, and any marketing approval, if granted, may have significant limitations on its use. In addition, future discussions with the EMEA or FDA may impact the amount of data needed and timelines for review, which may differ materially from Gilead's current projections. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead's Annual Report on Form 10-K for the year ended December 31, 2006 filed 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.

CONTACT: Gilead Sciences, Inc. Nathan Kaiser, 650-522-1853 Amy Flood, 650-522-5643 SOURCE: Gilead Sciences, Inc.