Sirtris Pharmaceuticals, Inc. Announces Pricing of Its Initial Public Offering

Sirtris Pharmaceuticals, Inc. (NASDAQ: SIRT), a biopharmaceutical
company focused on discovering and developing small molecule drugs to
treat diseases of aging such as Type 2 Diabetes, today announced the
pricing of its initial public offering of 6,000,000 shares of its
common stock at $10.00 per share, before underwriting discounts and
commissions. All of the common stock is being offered by Sirtris. In
addition, Sirtris has granted the underwriters a 30-day option to
purchase up to an additional 900,000 shares to cover over-allotments,
if any. J.P. Morgan Securities Inc. is acting as the sole book-running
manager and CIBC World Markets Corp., Piper Jaffray & Co., JMP
Securities LLC, and Rodman & Renshaw, LLC are acting as co-managers
for the offering. The shares will trade on the NASDAQ Global Market
under the symbol "SIRT."

A registration statement relating to these securities was declared
effective by the Securities and Exchange Commission on May 22nd, 2007.
The public offering is being made by means of a written prospectus.
Copies of the final prospectus relating to the offering may be
obtained from: J.P. Morgan Securities Inc., Attention: Prospectus
Department, 4 Chase Metrotech Center, CS Level, Brooklyn, NY 11245.
Phone: (718) 242-8002. Email: addressing.services@jpmorgan.com.

This press release shall not constitute an offer to sell or the
solicitation of an offer to buy, nor shall there be any sale of these
securities in any state in which such offer, solicitation or sale
would be unlawful prior to their registration or qualification under
the securities laws of any such state.

About Sirtris Pharmaceuticals

Sirtris Pharmaceuticals is a biopharmaceutical company focused on
discovering and developing proprietary, orally available, small
molecule drugs with the potential to treat diseases associated with
aging, including metabolic diseases such as Type 2 Diabetes. Our drug
candidates are designed to mimic certain beneficial health effects of
calorie restriction, without requiring a change in eating habits, by
activation of sirtuins, a recently discovered class of enzymes. The
company's headquarters are in Cambridge, Massachusetts.