EXHIBIT 99.1

ARIAD Raises Additional $8.1 Million Through Sale of Additional Common Stock

    CAMBRIDGE, Mass.--(BUSINESS WIRE)--Aug. 19, 2005--ARIAD
Pharmaceuticals, Inc. (Nasdaq: ARIA) today announced the completion of
the sale of 1,125,000 additional shares of its common stock pursuant
to the full exercise of the option granted to the underwriters of its
previously announced public offering to purchase additional shares.
The shares were priced at $7.20 per share resulting in gross proceeds
to ARIAD of $8.1 million.
    Lehman Brothers Inc. acted as sole book-running manager in this
offering. Lazard Capital Markets LLC and SG Cowen & Co., LLC acted as
co-managers.
    This press release does not constitute an offer to sell or the
solicitation of an offer to buy any of the securities, nor shall there
be any sale of the securities in any state in which such offer,
solicitation or sale would be unlawful prior to registration or
qualification under the securities laws of any such state. A
prospectus supplement relating to these securities has been filed with
the Securities and Exchange Commission. This offering of the shares of
common stock was made only by means of the prospectus supplement and
related prospectus, a copy of which is available from Lehman Brothers,
Inc., Prospectus Department, c/o ADP Financial Services, Integrated
Distribution Services, 1155 Long Island Avenue, Edgewood, New York
11717, monica_castillo@adp.com or at the Securities and Exchange
Commission's website at www.sec.gov.
    ARIAD is engaged in the discovery and development of breakthrough
medicines to treat cancer by regulating cell signaling with small
molecules.

    CONTACT: Edward Fitzgerald (Investors)
             617-621-2345
                 or
             Pure Communications
             Sheryl Seapy (Media)
             949-608-0841