EXHIBIT 99.1

ARIAD Initiates First Clinical Trial of Oral AP23573 in Patients with
                  Relapsed and/or Refractory Cancers

    CAMBRIDGE, Mass.--(BUSINESS WIRE)--May 26, 2005--

       Study Focuses On Safety, Dosing, Anti-cancer Activity and
                           Bioavailability

    ARIAD Pharmaceuticals, Inc. (Nasdaq:ARIA) today announced
initiation of enrollment of patients with relapsed and/or refractory
cancers in the first multi-center Phase 1b clinical trial of the oral
dosage form of its novel mTOR inhibitor, AP23573, which was recently
designated as a fast-track product by the U.S. Food and Drug
Administration for the treatment of sarcomas. Oral administration
(tablets) should permit greater flexibility in dosing and greater
convenience for patients, reducing dependency on a hospital or clinic
based treatment regimen.
    This non-randomized, dose-escalation study will evaluate the
safety, anti-cancer activity, pharmacokinetics, and bioavailability of
AP23573 tablets administered in three different oral dosing regimens.
Up to approximately 150 cancer patients will be enrolled in the trial
at three to five leading cancer centers in the United States.
    An intravenous dosage form of AP23573 is currently being studied
in multiple Phase 2 and 1b clinical trials in patients with
hematologic malignancies and solid tumors, including bone and
soft-tissue sarcomas, prostate, breast, ovarian, non-small-cell lung
and brain cancers. In studies conducted to date, AP23573 has exhibited
a favorable safety profile and broad anti-cancer activity.
    "The initiation of patient enrollment in the first clinical trial
of our newly developed oral dosage form of AP23573 represents another
major milestone for ARIAD," said Harvey J. Berger, M.D., chairman and
chief executive officer of ARIAD. "Based on the clinical results and
patient benefit seen to date with the intravenous form of AP23573, we
expect to move quickly through this oral bridging study which should
allow us to proceed with one or both dosage forms in key registration
trials."
    "The availability of both dosage forms should provide added
flexibility and therapeutic options as we develop AP23573 as a
fast-track product for patients with sarcoma," said Camille L.
Bedrosian, chief medical officer of ARIAD.

    About AP23573

    The small-molecule drug, AP23573, starves cancer cells and shrinks
tumors by inhibiting the critical cell-signaling protein, mTOR, which
regulates the response of tumor cells to nutrients and growth factors,
and controls tumor blood supply and angiogenesis through effects on
Vascular Endothelial Growth Factor (VEGF) in tumor and endothelial
cells. AP23573 also blocks the proliferation and migration of vascular
smooth muscle cells, the primary cause of narrowing and reblockage of
injured arteries, and is an analog of sirolimus, another mTOR
inhibitor that has been approved for use in drug-eluting stents.
AP23573 is currently in Phase 1 and 2 clinical trials in patients with
solid tumors and hematologic cancers. AP23573 has been designated a
fast-track product by the U.S. Food and Drug Administration for the
treatment of soft tissue and bone sarcomas.

    About ARIAD

    ARIAD is engaged in the discovery and development of breakthrough
medicines to treat disease by regulating cell signaling with small
molecules. The Company is developing a comprehensive approach to
patients with cancer that addresses the greatest medical need -
aggressive and advanced-stage cancers for which current treatments are
inadequate. Medinol Ltd. also is developing stents and other medical
devices that deliver ARIAD's lead cancer product candidate to prevent
reblockage at sites of vascular injury following stent-assisted
angioplasty. ARIAD has an exclusive license to pioneering technology
and patents related to certain NF-(kappa)B treatment methods, and the
discovery and development of drugs to regulate NF-(kappa)B
cell-signaling activity, which may be useful in treating certain
diseases. Additional information about ARIAD can be found on the Web
at http://www.ariad.com.

    Some of the matters discussed herein are "forward-looking
statements" within the meaning of the Private Securities Litigation
Reform Act of 1995. Such statements are identified by the use of words
such as "anticipate," "estimate," "expect," "project," "intend,"
"plan," "believe," and other words and terms of similar meaning in
connection with any discussion of future operating or financial
performance. Such statements are based on management's current
expectations and are subject to certain factors, risks and
uncertainties that may cause actual results, outcome of events, timing
and performance to differ materially from those expressed or implied
by such forward-looking statements. These risks include, but are not
limited to, risks and uncertainties regarding the Company's ability to
accurately estimate the timing and actual research and development
expenses and other costs associated with the preclinical and clinical
development and manufacture of our product candidates, the adequacy of
our capital resources and the availability of additional funding,
risks and uncertainties regarding our ability to manufacture our
product candidates on a commercial scale or to supply our product
candidates to our collaborator for use in its product candidates,
risks and uncertainties regarding our and our collaborator's ability
to successfully enroll and conduct preclinical and clinical studies of
product candidates, including our product candidate to treat cancer
described in this release and our collaborator's medical device
product candidates to treat vascular disease, risks and uncertainties
that clinical trial results at any phase of development may be adverse
or may not be predictive of future results or lead to regulatory
approval of any of our or our collaborator's product candidates, risks
and uncertainties of third-party intellectual property claims relating
to our and our collaborator's product candidates, and risks and
uncertainties relating to regulatory oversight, the timing, scope,
cost and outcome of legal proceedings, including litigation concerning
our NF-(kappa)B patent portfolio, future capital needs, key employees,
dependence on our collaborators and manufacturers, markets, economic
conditions, products, services, prices, reimbursement rates,
competition and other risks detailed in the Company's public filings
with the Securities and Exchange Commission, including ARIAD's Annual
Report on Form 10-K, as amended, for the fiscal year ended December
31, 2004. The information contained in this document is believed to be
current as of the date of original issue. The Company does not intend
to update any of the forward-looking statements after the date of this
document to conform these statements to actual results or to changes
in the Company's expectations, except as required by law.

    CONTACT: ARIAD Pharmaceuticals, Inc.
             Investors:
             Tom Pearson, 617-621-2345
             or
             Media:
             Pure Communications:
             Andrea Johnston, 910-681-1088