POWER OF ATTORNEY



      I hereby constitute and appoint each of Robert E. Farrell, Jr. and Joseph Vittiglio, Esq.,
signing singly, my true and lawful attorney-in-fact to:

(1)	execute for and on my behalf, in my capacity as a director of Oscient
Pharmaceuticals Corporation (the "Company"), 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 my behalf that may be necessary or
desirable to complete and execute any such Form 3, 4 or 5 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 to my benefit, in my best
interest, or that I am legally required to do, it being understood that the documents
executed by such attorney-in-fact's discretion.

      I hereby grant 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 I 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.  I acknowledge that
the attorneys-in-fact, in serving in such capacity at my request, are not assuming, nor is
the Company assuming, any of my 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 I am no longer
required to file Forms 3, 4 and 5 with respect to my holdings of and transactions in
Company securities, unless I earlier revoke it in a signed writing delivered to the
attorneys-in-fact.

	IN WITNESS WHEREOF, I have caused this Power of Attorney to be executed
as of this 31st day of May 2006.



					___________________________________
					William R. Mattson, Jr.
      					Director, Oscient Pharmaceuticals Corporation