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                                                                    EXHIBIT 99.1


Contact:     Peyton Marshall               Jill Sawdon
             Chief Financial Officer       Director of Corporate Communications
             The Medicines Company         The Medicines Company
             (617) 225-9099 (ph)           (617) 225-9099 (ph)
             (617) 225-2397 (fx)           (617) 225-2397 (fx)



For Immediate Release




                 THE MEDICINES COMPANY UPDATES REVENUE GUIDANCE


CAMBRIDGE, MA, OCTOBER 3, 2001 - The Medicines Company (NASDAQ: MDCO) announced
today that due to a more rapid than expected adoption by doctors of a shorter
duration regimen of ANGIOMAX(R) (bivalirudin) and the need to expand its sales
force in target hospitals it has lowered previous revenue guidance for 2001 and
2002.

The Company now expects revenues of $13 to $14 million in 2001, and revenues of
$36 to $41 million in 2002. Previous revenue guidance for 2001 suggested
revenues in the range of $18 to 22 million and 2002 revenues of approximately
$45 to 55 million. For the quarter ended September 30, 2001, the Company expects
to report revenues of approximately $3.5 million.

Despite lower than expected revenues, the Company is ahead of its forecasted
expectations for use in patients, demonstrating strong acceptance of ANGIOMAX by
the hospitals and doctors where its sales force has been active to date. The
Company is also ahead of its forecasted schedule with respect to hospital
stockings and formulary adoptions. As of September 28, of the 515 hospitals
called on by the Company's sales force, 58% (299) have stocked ANGIOMAX and 39%
(200) have ANGIOMAX on formulary, both ahead of the Company's expectations.

Based on customer acceptance of ANGIOMAX, the Company announced in July that it
would increase the size of the Company's sales organization to adequately
resource all 750 target hospitals. As of October 1, the sales force has been
increased by 30% and the Company now has 90 Representatives, Regional Account
Specialists, National Account Managers, Regional Managers and Medical Science
Liaisons dedicated to selling ANGIOMAX.
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While the Company anticipated a gradual reduction in patient usage over time, it
is finding that doctors are moving more quickly toward shorter infusions in
actual practice. In the marketplace today, the majority of ANGIOMAX-treated
patients are being treated with one vial. As a result, while the number of
patients receiving ANGIOMAX therapy is slightly ahead of the Company's forecast,
the vial use is behind the Company's launch forecast. Since the Company's launch
forecast anticipated the reduction in duration of infusion per patient over the
first three years of launch, it believes that the impact of this earlier
transition will primarily be felt in the first two years of launch.

 "We estimate that we are approximately 60 days behind our launch ramp for
revenue growth due to lower vial per patient use. As is common with drugs in the
hospital, doctors are tending to use shorter duration infusions of ANGIOMAX,
resulting in fewer vials used per patient. However, by many objective measures
the commercial launch of ANGIOMAX has been successful with strong stocking and
formulary adoption and high levels of patient usage in hospitals we have reached
to date," said Dr. Clive A. Meanwell, Executive Chairman.

"We are very encouraged by our success in the hospitals we have resourced to
date. Our progress reinforces our belief that as we expand our hospital coverage
and reach more patients, ANGIOMAX sales will accelerate on a trajectory
consistent with our original expectations," said David M. Stack, President and
Chief Executive Officer. "We believe ANGIOMAX delivers significant benefits to
patients and hospitals alike, and we are confident that its effectiveness,
safety profile and potential cost savings compared to heparin will continue to
attract new customers in the years ahead."

Clive Meanwell will host a conference call tomorrow morning at 8:30 AM Eastern
Time. To participate in the call, please dial 800.523.6069. International
participants may dial 1.847.413.4838. If you cannot participate in the live
call, a replay will be available for one week. To listen to the replay, please
dial 888.843.8954, or 1.630.652.3043 internationally and enter code 4832965.
Alternatively, a webcast will be available for one week on our homepage,
www.themedicinescompany.com.

The Medicines Company was founded in 1996 to acquire, develop and commercialize
selected pharmaceutical products in late stages of development and approved
products. In December 2000, the Company received marketing approval from the
U.S. Food and Drug Administration for ANGIOMAX for use as an anticoagulant in
combination with aspirin in patients with unstable angina undergoing coronary
balloon angioplasty. The Company began selling ANGIOMAX in the United States in
January 2001. The Company expects ANGIOMAX to be the cornerstone product of a
planned acute hospital franchise. The Company is also developing a second
product, CTV-05, a proprietary biotherapeutic agent with a potentially broad
range of applications in the treatment of gynecological and reproductive
infections. Additional information about the company and its products can be
found at www.themedicinescompany.com.
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This press release contains forward-looking statements that involve a number of
risks and uncertainties. For this purpose, any statements contained herein that
are not statements of historical fact may be deemed to be forward-looking
statements. Without limiting the foregoing, the words, "believes,"
"anticipates," "plans," "expects," "intends," and similar expressions are
intended to identify forward-looking statements. Important factors that could
cause actual results to differ materially from the expectations described in
these forward-looking statements are set forth under the caption "Risk Factors"
in the Company's Registration Statement on Form S-1 filed with the Securities
and Exchange Commission on May 23, 2001 and incorporated herein by reference.
These risk factors include risks as to the commercial success of ANGIOMAX; how
long the Company will be able to operate on its existing capital resources;
whether the Company's products (other than ANGIOMAX for its approved indication)
will advance in the clinical trials process, the timing of such clinical trials,
whether the clinical trial results will warrant continued product development,
whether and when, if at all, the Company's products will receive approval from
the U.S. Food and Drug Administration or equivalent regulatory agencies, and for
which indications, and, if such products receive approval, whether they will be
successfully marketed; the Company's history of net losses; and the Company's
dependence on third parties, including manufacturers, suppliers, sales agents
and collaborators.