PRAECIS PHARMACEUTICALS INCORPORATED Announces Technology Transfer and Option Agreement with Gilead Sciences, Inc. to Utilize D

PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS)
today announced that it has signed a technology transfer and option
agreement with Gilead Sciences, Inc. Under the agreement, PRAECIS will
utilize its proprietary DirectSelect(TM) technology to identify lead
drug candidates for an antiviral target supplied by Gilead. The
companies will collaborate to identify lead molecules that have
defined activities against the antiviral target. Each company will
fund its own resources during the course of the research
collaboration. PRAECIS will own any lead molecules identified during
the course of the research collaboration. Gilead has an exclusive
option to enter into a license agreement for any lead molecules so
identified.

   Commenting on the collaboration, Kevin F. McLaughlin, President
and Chief Executive Officer of PRAECIS, stated, "We are pleased to be
working with Gilead against a therapeutic target in which we have
strong mutual interest. This is our first collaboration using our
DirectSelect(TM) technology and Gilead, a leader in antiviral
research, brings an extensive amount of expertise that should be very
beneficial in helping to drive this program."

   William Lee, Ph.D., Senior Vice President of Research of Gilead,
stated, "PRAECIS has created a powerful technology for identifying
lead structures. We look forward to collaborating with PRAECIS to
explore the ability of DirectSelect(TM) technology to identify novel
drug candidates."

   About DirectSelect(TM) Technology

   PRAECIS has developed a chemistry-driven technology, called
DirectSelect(TM), which it believes will facilitate the drug discovery
process. The technology is based upon the creation of multiple,
numerically large (10 to the seventh to >10 to the ninth), encoded
libraries of drug-like structures that can be rapidly screened to
identify individual structures, or families of structures, with
affinity for a macromolecular target.

   The premise behind the DirectSelect(TM) technology is that the
odds of identifying hits with higher affinity and enhanced selectivity
for a macromolecular target can be improved by increasing the numeric
size and "chemical space" interrogated by the target. In addition,
access to multiple, structurally diverse families should improve the
likelihood of identifying a lead molecule with a favorable safety
profile in vivo. Combinatorial libraries of small molecules have
traditionally been constrained to relatively low numbers (up to tens
of thousands) of constituents due to technical limitations associated
largely with deconvolution. PRAECIS has systematically addressed these
challenges by focusing its efforts on marrying validated chemistry
methods with unique screening and deconvolution steps.

   The chemistry approach adopted by PRAECIS is to create libraries
that are both rich in numbers of compounds and structural diversity.
PRAECIS has succeeded in constructing multiple libraries that
currently aggregate to greater than 5 billion compounds. PRAECIS'
vision is to continue the diversification of its libraries through the
addition of new scaffolds and building blocks.

   PRAECIS intends to continue to develop and enhance its
DirectSelect(TM) technology, enter into pharmaceutical partnerships
for drug discovery and development utilizing this technology, and
utilize the technology to expand its own proprietary development
pipeline.

   About PRAECIS

   PRAECIS PHARMACEUTICALS INCORPORATED is a biopharmaceutical
company focused on the discovery and development of innovative
therapies that either address unmet medical needs or offer
improvements over 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. PRAECIS has
received approval to market Plenaxis(R) in both the United States and
Germany.

   This news release contains forward-looking statements, including
statements regarding the Company's plans for seeking partnerships
relating to, as well as the internal use of, its DirectSelect(TM)
technology. These statements are based on the Company's current
beliefs and expectations as to future outcomes and are not guarantees
of future events or performance. These statements are subject to
numerous risks, uncertainties and assumptions that could cause actual
events and results to differ from those anticipated or projected,
including, but not limited to, the Company's ability to continue
development of and successfully partner its DirectSelect(TM)
technology, 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 various risks discussed in the
Company's Annual Report on Form 10-K for the year ended December 31,
2005. 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.