AUTHORIZATION LETTER




July 27, 2005

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549
Attn: Filing Desk


To Whom It May Concern:

By means of this letter I authorize Mark L. Perry, John F
Milligan, Gregg H. Alton, ESQ.and Matthew K. Au, or any of them
individually, to sign on my behalf all forms required
under Section 16(a) of the Securities Exchange Act of
1934, as amended, relating to transactions involving the
stock of derivative securities of Gilead Sciences, Inc.
(the "Company"). Any of these individuals is accordingly
authorized to sign any Form 3, Form 4, Form 5 or
amendment thereto which I am required to file with the
same effect as if I had signed them myself.

This authorization shall remain in effect until revoked
in writing by me.


Yours truly,



/s/ Taiyin Yang















POWER OF ATTORNEY

	Know all by these presents, that the undersigned
hereby constitutes and appoints
each of Mark L. Perry, John F. Milligan, Gregg H.
Alton, Esq. and Matthew K. Au signing individually, the undersigned's true
and lawful attorneys-in-fact and agents to:

(1)	execute for and on behalf of the
undersigned, an officer or director  of
Gilead Sciences, Inc. (the "Company"), Forms 3, 4
and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934, as amended (the
"Exchange Act") and the rules thereunder;

(2)	do and perform any and all acts for and
on behalf of the undersigned
that may be necessary or desirable to complete and
execute such Form 3, 4 or 5, complete and execute
and amendment or amendments thereto, and timely file
such forms or amendments with United States
Securities and Exchange Commission and any stock
exchange or similar authority; and

(3)	take any other action of any nature
whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-
fact, may be of benefit, in the best interest of, or
legally required by, the undersigned, it being
understood that the documents executed by such
attorney-in-fact on behalf of the undersigned
pursuant to this Power of Attorney shall be in such
form and shall contain such terms and conditions as
such attorney-in-fact may approve in such attorney-
in-fact's discretion.

The undersigned hereby grants to each such attorney-
in-fact full power and
authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in
the exercise of any of the rights and powers herein
granted, fully to all intents and purpose as the
undersigned might or could do if personally present, with
full power of substitution or revocation, hereby
ratifying and confirming all that such attorney-in-fact,
or such attorney-in-fact's substitute or substitutes,
shall lawfully do or cause to be done by virtue of this
power of attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the
request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the
Exchange Act.

	This Power of Attorney shall remain in full force
and effect until the earliest to occur of (a) the
undersigned is no longer required to file Forms 3, 4 and
5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, (b)
revocation by the undersigned in a signed writing
delivered to the foregoing attorney's-in-fact or (c) as
to any attorney-in-fact individually, until such
attorney-in-fact shall no longer be employed by the
Company.

	IN WITNESS WHEREOF, the undersigned has caused this
Power of Attorney to be executed as of this 27th day of
July, 2005.


/s/ Taiyin Yang