WELLESLEY, MA - August 10, 2005 - Coley Pharmaceutical Group, Inc. today announced the initial public offering of 6,000,000 shares of its common stock at a price of $16.00 per share, before underwriting discounts and commissions. Shares of Coley's common stock will be traded on the Nasdaq National Market beginning August 10, 2005 under the trading symbol "COLY". Coley has granted the underwriters of the initial public offering a 30-day over-allotment option to purchase an additional 900,000 shares. In a separate private placement, an additional 625,000 shares will be purchased by Coley’s collaboration partner, Pfizer, Inc., at $16.00 per share, under the terms of a worldwide license agreement announced with Coley in March 2005. Merrill Lynch & Co. was the book runner for the offering with J.P. Morgan acting as co-lead. Lazard and Leerink Swann are acting as co-managers for the offering.

Proceeds from the offering are expected to be approximately $97,594,000 or $110,986,000 if the underwriters exercise their over-allotment option in full, after deducting the underwriting discounts and commissions and the estimated offering expenses.

Copies of the final prospectus relating to the offering may be obtained by contacting Merrill Lynch & Co., 4 World Financial Center, New York, New York 10080 USA (telephone: +1.212.449.1000).

A registration statement relating to these securities was declared effective by the Securities and Exchange Commission on August 9, 2005. The public offering is being made by means of a written prospectus forming part of the effective registration statement.

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 or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Coley Pharmaceutical Group
Coley Pharmaceutical Group, Inc. is an international biopharmaceutical company, headquartered in Wellesley, Massachusetts , USA, that discovers and develops TLR Therapeutics™, a new class of investigational drug candidates that direct the human immune system to fight cancers, infectious diseases, asthma and allergy. Coley has established a pipeline of four TLR Therapeutic product candidates currently advancing through clinical development either independently or with partners, and additional product candidates in preclinical development. Coley has product development, research and license agreements with Pfizer, sanofi-aventis, Chiron, the United States government and GlaxoSmithKline.

Safe Harbor Statement
Certain statements in this news release concerning Coley's business are considered "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, those relating to Coley’s ability to advance the discovery, development and commercialization of its TLR Therapeutics. Any or all of the forward-looking statements in this press release may turn out to be wrong. They can be affected by inaccurate assumptions Coley might make or by known or unknown risks and uncertainties, including, but not limited to: the early stage of product development; uncertainties as to the future success of ongoing and planned clinical trials; and the unproven safety and efficacy of products under development. Consequently, no forward-looking statement can be guaranteed, and actual results may vary materially. Coley undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise, except as required by applicable law.