POWER OF ATTORNEY

Know all by these presents, that the undersigned

hereby constitutes and appoints each of Kurt Leutzinger,

Bryce A. Roberts, James Maguire and Paul Lubetkin the undersigned's

 true and lawful attorney-in-fact to:

(i) execute for and on behalf of the undersigned, in the

undersigned's capacity as an officer and/or director of Pharmasset,

Inc. (the "Company"), Form ID and Forms 3, 4, and 5 in accordance

with Section 16(a) of the Securities Exchange Act of 1934 and

the rules thereunder;

(2) do and perform any and all acts for and on behalf of

the undersigned which may be necessary or desirable to complete

and execute any such Form ID and Form 3, 4, or 5, complete and

execute any amendment or amendments thereto, and timely file such

form with the United States Securities and Exchange Commission and

any stock exchange or similar authority; and

(3) take any other action of any type whatsoever in

connection with the foregoing which, in the opinion of such

attorney-in-fact, may be of benefit to, 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, as fully to all intents and purposes 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 Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and

effect until 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, unless earlier

revoked by the undersigned in a signed writing delivered to the

foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this

Power of Attorney to be executed as of this 30th day of March,

2010.

/s/ Michael J. Otto











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PHLEGAL: #1737349 v1 (118JP01!.DOC)





PHLEGAL: #1737349 v1 (118JP01!.DOC)