POWER OF ATTORNEY

	Know all by these presents, that the undersigned
hereby constitutes and appoints each of Safi R. Bahcall,
Ph.D., the President and Chief Executive Officer of Synta
Pharmaceuticals Corp. (the "Company"), Keith S. Ehrlich,
the Vice President, Finance and Administration, Chief
Financial Officer of the Company, and Wendy E. Rieder,
the Vice President, Intellectual Property and Legal
Affairs, General Counsel of the Company, and Brian Keane,
Daniel T. Kajunski, and Ann Margaret Eames of Mintz,
Levin, Cohn, Ferris, Glovsky and Popeo, P.C., signing
singly, with full power of substitution, the
undersigned's true and lawful attorney-in-fact to:

	(1)	execute for and on behalf of the undersigned,
in the undersigned's capacity as an officer, director
			and/or 10% shareholder of the Company,
forms and authentication documents for EDGAR Filing
		Access;

	(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
forms and authentication documents;

	(3)	execute for and on behalf of the undersigned,
in the undersigned's capacity as an officer,
director and/or 10% shareholder of the
Company, Forms 3, 4 and 5 in accordance with
Section 16(a) of the Securities Exchange Act
of 1934 and the rules thereunder;

	(4)	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 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

	(5)	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 interests 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, as amended.

	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 this 27th day of January
2007.



/s/ Eric W. Jacobson
Signature


Eric W. Jacobson
Print Name