Gilead Submits Marketing Applications in the United States and European Union for Viread(R) (Tenofovir Disoproxil Fumarate) for the Treatment of Chronic Hepatitis B

Gilead Sciences, Inc. (Nasdaq: GILD) today announced that it has
submitted a supplemental New Drug Application (sNDA) to the U.S. Food
and Drug Administration (FDA) and a Type II variation to the European
Medicines Agency (EMEA) for marketing approval of Viread(R) (tenofovir
disoproxil fumarate) for the treatment of chronic hepatitis B in
adults. Viread is already approved in the United States and European
Union for the treatment of HIV as part of combination antiretroviral
therapy.

"New treatments are critically important in the fight against
chronic hepatitis B, a potentially life-threatening infection that
impacts millions of people worldwide," said Eugene Schiff, MD, Chief
of the Division of Hepatology and Director of the Center for Liver
Diseases at the University of Miami School of Medicine. "We've made
great progress in our ability to diagnose and treat the disease, but a
significant unmet medical need remains and ongoing efforts in research
and development are essential."

The submissions contain data from two Phase III pivotal clinical
trials, Studies 102 and 103, in patients chronically infected with the
hepatitis B virus (HBV). These studies evaluate the efficacy, safety
and tolerability of Viread compared to Gilead's Hepsera(R) (adefovir
dipivoxil). Gilead announced the primary results from Study 102 and
103 on June 6 and June 25, 2007, respectively. Detailed data from both
studies will be described in late-breaker presentations at the annual
meeting of the American Association for the Study of Liver Diseases
(The Liver Meeting 2007) in Boston, Massachusetts, November 2-6.

"The active ingredient in Viread -- tenofovir disoproxil fumarate
-- is the most widely prescribed molecule for the treatment of HIV in
the United States," said Franck Rousseau, MD, Vice President, Clinical
Research, Gilead Sciences. "With positive data from two pivotal
studies now available, we look forward to extending the use of this
important therapy to patients with chronic hepatitis B."

Chronic hepatitis B affects more than 400 million people
worldwide. The complications of chronic hepatitis B, which include
liver cancer and cirrhosis, kill up to 1.2 million people each year,
making it one of the world's top 10 causes of death. In the United
States, an estimated 1.3 million people are currently living with
chronic hepatitis B, of whom more than half are Asian American. In the
European region, one million people are estimated to become infected
with HBV each year and approximately 90,000 go on to develop chronic
hepatitis B.

While there is no cure for the disease, anti-HBV medications can
have beneficial effects on chronic hepatitis B throughout the course
of infection, potentially preventing fatal liver damage and liver
cancer. In many cases, this requires prolonged treatment over the
course of many months or years.

About Viread (tenofovir disoproxil fumarate) for HIV

In the United States, Viread is indicated in combination with
other antiretroviral agents for the treatment of HIV-1 infection.

Lactic acidosis and severe hepatomegaly with steatosis, including
fatal cases, have been reported with the use of nucleoside analogues
alone or in combination with other antiretrovirals. Viread is not
approved for the treatment of chronic hepatitis B virus (HBV)
infection and the safety and efficacy of Viread have not been
established in patients coinfected with HBV and HIV. Severe acute
exacerbations of hepatitis B have been reported in patients who have
discontinued Viread. Hepatic function should be monitored closely with
both clinical and laboratory follow-up for at least several months in
patients who are co-infected with HIV and HBV and discontinue Viread.
If appropriate, initiation of anti-hepatitis B treatment may be
warranted.

It is important for patients to be aware that anti-HIV medicines
including Viread do not cure HIV infection or AIDS, and do not reduce
the risk of transmitting HIV to others.

Renal impairment, including cases of acute renal failure and
Fanconi syndrome (renal tubular injury with severe hypophosphatemia),
has been reported in association with the use of Viread. It is
recommended that creatinine clearance be calculated in all patients
prior to initiating therapy with Viread and as clinically appropriate
during therapy. Routine monitoring of calculated creatinine clearance
and serum phosphorous should be performed in patients at risk for
renal impairment. Dosing interval adjustment and close monitoring of
renal function are recommended in all patients with creatinine
clearance less than 50mL/min. Viread should be avoided with concurrent
or recent use of a nephrotoxic agent.

The U.S. package insert advises that co-administration of Viread
and didanosine should be undertaken with caution. Patients should be
monitored closely for didanosine-associated adverse events and
didanosine should be discontinued if these occur. Patients on
atazanavir and lopinavir/ritonavir plus Viread should be monitored for
Viread-associated adverse events and Viread should be discontinued if
these occur. When co-administered with Viread, it is recommended that
atazanavir be given with ritonavir 100 mg. Atazanavir without
ritonavir should not be co-administered with Viread.

Decreases in bone mineral density (BMD) at the lumbar spine and
hip have been seen with the use of Viread. The effect on long-term
bone health and future fracture risk is unknown. Cases of osteomalacia
(associated with proximal renal tubulopathy) have been reported in
association with the use of Viread.

Changes in body fat have been observed in patients taking anti-HIV
medicines. The mechanism and long-term health effect of these changes
are unknown. Immune Reconstitution Syndrome has been reported in
patients treated with combination therapy, including Viread.

The most common adverse events among patients receiving Viread
with other antiretroviral agents in a pivotal clinical study (Study
903) were mild to moderate gastrointestinal events and dizziness.
Moderate to severe adverse events occurring in more than 5 percent of
patients receiving Viread included rash (rash, pruritis, maculopapular
rash, urticaria, vesiculobullous rash and pustular rash), headache,
pain, diarrhea, depression, back pain, fever, nausea, abdominal pain,
asthenia (weakness) and anxiety. In another pivotal study (Study 907),
less than 1 percent of patients discontinued participation because of
gastrointestinal events.

For full prescribing information outside of the United States,
physicians should consult their local product labeling.

The parent compound of Viread was discovered through a
collaborative research effort between Dr. Antonin Holy, Institute for
Organic Chemistry and Biochemistry, Academy of Sciences of the Czech
Republic (IOCB) in Prague and Dr. Erik DeClercq, Rega Institute for
Medical Research, Katholic University in Leuven, Belgium.

About Hepsera (adefovir dipivoxil)

Hepsera, a nucleotide analogue, works by inhibiting HBV DNA
polymerase, an enzyme involved in the replication of the virus in the
body.

In the United States, Hepsera is indicated for the treatment of
chronic hepatitis B in adults with evidence of active viral
replication and either evidence of persistent elevations in serum
aminotransferases (ALT or AST) or histologically active disease.

The U.S. package insert advises that the adverse reactions
considered at least possibly related to treatment reported in 3
percent or greater of patients in the first 48 weeks in Hepsera
pivotal clinical studies were asthenia, headache, abdominal pain,
nausea, flatulence, diarrhea and dyspepsia. With extended treatment,
mild to moderate increases in serum creatinine were observed
uncommonly in patients with chronic hepatitis B and compensated liver
disease treated with Hepsera for a median of 49 weeks up to a maximum
of 240 weeks. Changes in serum creatinine were observed very commonly
in patients pre- and post-transplantation with lamivudine-resistant
liver disease and multiple risk factors for changes in renal function
who were treated with Hepsera for up to 129 weeks, with a median time
on treatment of 19 and 56 weeks, respectively. Clinical and laboratory
evidence of exacerbations of hepatitis have occurred after
discontinuation of treatment with antiviral therapies for hepatitis B,
including Hepsera. Special warnings and precautions for use are
included in the U.S. package insert regarding monitoring of renal
function, post-treatment exacerbations of hepatitis, and the
occurrence of lactic acidosis and severe hepatomegaly with steatosis.
For physicians in the United States, dosing instructions for patients
with underlying renal impairment and for patients co-infected with HIV
are also provided in the U.S. package insert, which is available for
download online at www.hepsera.com.

For full prescribing information outside of the United States,
physicians should consult their local product labeling.

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.

Forward-Looking Statement

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 Viread for
chronic hepatitis B. For example, the FDA and EMEA may not approve
Viread for the treatment of chronic hepatitis B, and marketing
approval, if granted, may have significant limitations on its use and
physicians may not see advantages of Viread over other treatment
options and may therefore be reluctant to prescribe Viread for chronic
hepatitis B. 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 and its Quarterly Report on Form 10-Q for the first
and second quarters of 2007, as 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.

U.S. full prescribing information for Viread is available at
www.Viread.com

U.S. full prescribing information for Hepsera is available at
www.Hepsera.com

Viread and Hepsera are registered trademarks of Gilead Sciences,
Inc.

For more information on Gilead, please call the Gilead Public
Affairs Department at 1-800-GILEAD-5 (1-800-445-3235) or visit
www.gilead.com.