PRAECIS PHARMACEUTICALS INCORPORATED Announces Cessation of Plenaxis(R) Disposition Efforts; Plans to Explore Financing Alterna

PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS)
today reported that it will not be able to enter into by June 30, 2006
a license or sale transaction with respect to its Plenaxis(R) assets.
The Company said it will cease its previously announced process to
identify and consummate such a transaction. Accordingly, as previously
disclosed, the Company will work with the United States Food and Drug
Administration to discontinue the limited distribution of the product
in the United States as soon as reasonably practicable and will not
pursue further the commercialization of Plenaxis(R) outside the United
States. The Company will also promptly discontinue any remaining
Plenaxis(R)-related activities, except as necessary to support the
wind-down of product distribution in the United States. During this
wind-down, the Company will continue to evaluate potential
opportunities for these assets to the extent such opportunities arise.
Due to the termination of its active efforts to license or sell its
Plenaxis(R) assets, the Company currently estimates that it will
record a non-cash impairment charge of approximately $3.6 million in
the second quarter of 2006 related to the remaining value of
capitalized Plenaxis(R) inventory and equipment. The Company will also
record an additional charge in the second quarter of approximately
$3.9 million related to the present value of its remaining commitments
under certain of its Plenaxis(R) manufacturing and supply agreements.

   The Company continues to believe that its existing cash and
investments will be sufficient to meet its working capital and capital
expenditure needs, at current levels, through approximately the end of
2007. In an effort to ensure that the Company has available resources
to pursue its operations beyond 2007, the Company intends to actively
explore financing alternatives, as well as other strategic options
which may be available to achieve and enhance shareholder value. The
Company has engaged Canaccord Adams, an international investment
banking firm with significant expertise in the life sciences sector,
to advise and assist the Company in these efforts.

   The Company stated that there can be no assurance that these
efforts will result in additional financing for the Company or in any
other transaction. The Company does not currently intend to disclose
developments with respect to these efforts unless and until its Board
of Directors has approved a specific transaction.

   About PRAECIS

   PRAECIS PHARMACEUTICALS INCORPORATED is a biopharmaceutical
company focused on the discovery and development of novel compounds
that have the potential to address unmet medical needs or improve
existing therapies. PRAECIS has a novel MetAP-2 inhibitor, PPI-2458,
in clinical development for cancer indications, including
non-Hodgkin's lymphoma and solid tumors, as well as an innovative drug
discovery technology, DirectSelect(TM), which enables the generation
and practical use of ultra-large libraries for the discovery of orally
active compounds for drug development.

   This news release contains forward-looking statements, including,
but not limited to, statements regarding the expected timing and
effect of the Company's discontinuation of its Plenaxis(R) activities,
the Company's expected available resources through approximately the
end of 2007 and the Company's plans to actively explore financing
alternatives for the Company, as well as other strategic options which
may be available to achieve and enhance shareholder value. These
statements are based on the Company's current beliefs and expectations
as to future outcomes and are not guarantees of such outcomes or of
future performance. These statements are subject to numerous risks,
uncertainties and assumptions that could cause actual events or
results to differ from those expected or anticipated, including, but
not limited to, the Company's ability to successfully execute on, in a
timely manner and on favorable terms, a financing or other transaction
for the Company, the Company's ability to continue to manage operating
expenses and to retain key employees, unexpected expenditures, the
Company's ability to continue development of and successfully partner
PPI-2458 and its DirectSelect(TM) drug discovery technology,
unexpected results in ongoing and future clinical or preclinical
trials, the need for additional research and testing, including as a
result of unanticipated determinations by the FDA or foreign
regulatory authorities, as well as the risks set forth from time to
time in the Company's filings with the Securities and Exchange
Commission, including but not limited to the risks discussed in the
Company's Quarterly Report on Form 10-Q for the quarter ended March
31, 2006. The Company undertakes no obligation to update any
forward-looking statement made in this press release to reflect new
information, events or circumstances after the date of this release.

   Plenaxis(R) is a registered trademark of PRAECIS PHARMACEUTICALS
INCORPORATED.