Proposal Two—Ratification of Appointment of Independent Registered Public Accounting Firm

The affirmative vote of the holders of a majority of the shares of common stock present or represented and voting on the matter is needed to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2007.

How will votes be counted?

Each share of common stock is entitled to one vote. Shares will not be voted in favor of a matter, and will not be counted as voting on a matter (1) if the holder of the shares either withholds authority in the proxy to vote for a particular director nominee or nominees, or abstains from voting on a particular matter, or (2) if the shares are broker non-votes. As a result, withheld shares, abstentions and broker non-votes will have no effect on the outcome of voting on any of the proposals.

How does the board of directors recommend that I vote?

Our board of directors recommends that you vote:

Will any other business be conducted at the annual meeting?

Our board of directors does not know of any other business to be conducted or matters to be voted upon at the meeting. Under our by-laws, the deadline for stockholders to notify us of any proposals or nominations for director to be presented for action at the annual meeting has passed. If any other matter properly comes before the meeting, the persons named in the proxy card that accompanies this proxy statement will exercise their judgment in deciding how to vote, or otherwise act, at the meeting with respect to that matter.

Who pays for the solicitation of proxies?

We will bear the costs of soliciting proxies. In addition to solicitations by mail, our directors, officers and regular employees, without additional remuneration, may solicit proxies by telephone, facsimile, email, personal interviews and other means. We have requested brokerage houses, custodians, nominees and fiduciaries to forward copies of the proxy materials to the persons for whom they hold shares and request

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instructions for voting the proxies. We will reimburse the brokerage houses and other persons for their reasonable out-of-pocket expenses in connection with this distribution.

How and when may I submit a proposal for the 2008 annual meeting?

If you are interested in submitting a proposal for inclusion in the proxy statement and proxy card for our 2008 annual meeting, you need to follow the procedures outlined in Rule 14a-8 of the Securities Exchange Act of 1934. We must receive your proposal intended for inclusion in the proxy statement at our principal executive offices, 8 Campus Drive, Parsippany, New Jersey 07054 Attention:  Paul M. Antinori, Secretary, no later than December 23, 2007.

If you wish to present a proposal at the 2008 annual meeting, but do not wish to have the proposal considered for inclusion in the proxy statement and proxy card, you must also give written notice to us at the address noted above. Our by-laws specify the information that must be included in any such notice, including a brief description of the business to be brought before the annual meeting and the name of the stockholder proposing such business. We must receive this notice at least 60 days, but not more than 90 days, prior to May 24, 2008. However, if the date of the 2008 annual meeting is prior to May 4, 2008 or after July 23, 2008, we must receive your notice no earlier than the 90th day prior to the 2008 annual meeting and no later than the close of business on the later of (1) the 60th day prior to the 2008 annual meeting and (2) the 10th day following the date on which notice of the date of the meeting was mailed or public disclosure of the date of the meeting was made, whichever occurs first. If you fail to provide timely notice of a proposal to be presented at the 2008 annual meeting, the chairman of the meeting may exclude the proposal from being brought before the meeting.

HOUSEHOLDING OF ANNUAL MEETING MATERIALS

Some banks, brokers and other record holders may be participating in the practice of “householding” proxy statements and annual reports. This means that only one copy of our proxy statement and annual report may have been sent to multiple stockholders in your household. We will promptly deliver a separate copy of either document to you if you call or write us at the following address or phone number: The Medicines Company, 8 Campus Drive, Parsippany, New Jersey 07054, Attention: Investor Relations, (973) 656-1616. If you would like to receive separate copies of the annual report and proxy statement in the future, or if you are receiving multiple copies and would like to receive only one copy for your household, you should contact your bank, broker, or other nominee record holder, or you may contact us at the above address and phone number.

DISCUSSION OF PROPOSALS

Proposal One:  Election of Class 1 Directors

Our board of directors is divided into three classes and currently consists of four class 1 directors (William W. Crouse, T. Scott Johnson, John P. Kelley, and Hiroaki Shigeta), three class 2 directors (Robert J. Hugin, Clive A. Meanwell and Elizabeth H.S. Wyatt) and three class 3 directors (Armin M. Kessler, Robert G. Savage and Melvin K. Spigelman). The term of each class of directors is three years, and the terms of the three classes are staggered so that only one class is elected each year. At each annual meeting of stockholders, directors are elected to serve for a three-year term to succeed the directors of the same class whose terms are then expiring. The class 1, class 2 and class 3 directors were elected to serve until the annual meeting of stockholders to be held in 2007, 2008 and 2009, respectively, and until their respective successors are elected and qualified.

Our board of directors, on the recommendation of our nominating and corporate governance committee, has nominated William W. Crouse, T. Scott Johnson, John P. Kelley, and Hiroaki Shigeta for election as class 1 directors at the annual meeting. The persons named in the enclosed proxy card will vote

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to elect each of these nominees as a class 1 director, unless the proxy is marked otherwise. Each class 1 director will be elected to hold office until the 2010 annual meeting of stockholders and until his successor is elected and qualified. Each of the nominees is presently a director, and each has indicated a willingness to continue to serve as director, if elected. If a nominee becomes unable or unwilling to serve, however, the proxies may be voted for substitute nominees selected by our board of directors.

No director or executive officer of ours is related by blood, marriage or adoption to any other director or executive officer of ours. No director or officer of ours, or any employee of any such director or officer, is a party adverse to us or any of our subsidiaries, or has a material interest adverse to us or any of our subsidiaries, in any legal proceeding. No director or executive officer of ours has any interest, direct or indirect, by security holdings or otherwise, in any matter to be acted upon at the annual meeting, other than election to office.

Our board of directors recommends a vote FOR each of the nominees.

Director Nominees

Set forth below are the names of each nominee for class 1 director, the year in which each first became a director, their ages as of April 1, 2007, their positions and offices with us, if any, their principal occupations and business experience for at least the past five years, the names of other public companies for which they serve as a director and education.

WILLIAM W. CROUSE
Age: 64

William W. Crouse has been a director since April 2003. Since January 1994, Mr. Crouse has been a Managing Director of HealthCare Ventures, a venture capital firm with a focus on biotechnology companies. From 1987 to 1993, Mr. Crouse served as Worldwide President of Ortho Diagnostic Systems, a subsidiary of Johnson & Johnson that manufactures diagnostic tests for hospitals, and a Vice President of Johnson & Johnson International. Before joining Johnson & Johnson, Mr. Crouse was a Division Director of DuPont Pharmaceuticals Company, a pharmaceutical firm, where he was responsible for international operations and worldwide commercial development activities. Before joining Dupont, he served as President of Revlon Health Care Group’s companies in Latin America, Canada, and Asia/Pacific. He also held numerous management positions at E.R. Squibb & Sons, a pharmaceutical company. Mr. Crouse is currently the chairman of the board of directors of Uluru, Inc., a specialty pharmaceutical company, and a member of the Boards of Trustees of Lehigh University and the New York Blood Center. Mr. Crouse received a B.S. in finance and economics from Lehigh University and an M.B.A. from Pace University.

T. SCOTT JOHNSON
Age: 59

T. Scott Johnson has been a director since September 1996. Since July 1999, Dr. Johnson has been a partner at JSB Partners, L.P., an investment bank that he founded in 1999, which focuses on mergers and acquisitions, private financings and corporate alliances within the healthcare sector. From September 1991 to July 1999, Dr. Johnson served as a founder and managing director of MPM Capital, L.P., a venture capital firm. Dr. Johnson received both a B.S. and an M.D. from the University of Alabama.

JOHN P. KELLEY
Age: 53

John P. Kelley has been our President and Chief Operating Officer since December 2004 and a director since February 2005. Prior to joining us, Mr. Kelley held a series of positions at Aventis, an international pharmaceutical company. From September 2003 until September 2004, Mr. Kelley served as

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Senior Vice President, Global Marketing and Medical at Aventis, where he was accountable for worldwide brand management of Aventis’ core strategic brands and managed strategic alliances with partner companies. From September 2002 to September 2003, he served as Senior Vice President, Strategic Risk Officer for Aventis, advising the Management Board and Chief Executive Officer. From January 2000 to September 2002, Mr. Kelley served as Vice President, Head of Strategic Development of Aventis where he was responsible for leading the strategic planning process of the pharmaceutical division of Aventis as well as merger and acquisition activity. Prior to the formation of Aventis, he served as a Vice President, Commercial Director, U.S. at Hoechst Marion Roussel, Inc., a life sciences firm focused on pharmaceuticals and agriculture, from March 1998 through December 1999 and Mr. Kelley served as Vice President of Marketing of Hoechst Marion Roussel from 1995 to 1998. Mr. Kelley received a B.S. degree from Wilkes University and an M.B.A. from Rockhurst University.

HIROAKI SHIGETA
Age: 64

Hiroaki Shigeta has been a director since April 2007. Since October 1993, Mr. Shigeta has served in variety of senior management positions with Hoffman-La Roche, Inc., a pharmaceutical company, and its affiliates. From October 1993 to December 2000, Mr. Shigeta was the President and Chief Executive Officer of Nipon Roche KK, a pharmaceutical company and a Japanese affiliate of Roche Holding of Switzerland. From January 2001 to May 2002, Mr. Shigeta served as Chairman and Representative Director of Nipon Roche KK. From June 2002 to April 2003, Mr. Shigeta was a Member of the Board of Chugai Seiyaku KK, Tokyo, a majority-owned affiliate of Roche Holding of Switzerland and from January 2003 to December 2004, Mr. Shigeta was the U.S. Head, Far East Relations of Hoffman-La Roche, Inc. From January 2005 until June 2006, Mr. Shigeta has served as a consultant to various Japanese pharmaceutical companies. Mr. Shigeta has been a paid consultant to us since July 2006.

Other Current Directors

Set forth below are the names of each of our other current directors, the year in which each first became a director, their ages as of April 1, 2007, their positions and offices with us, if any, their principal occupations and business experience during the past five years, the names of other public companies for which they serve as a director and their education.

Directors Whose Terms Expire in 2008 (Class 2 Directors)

ROBERT J. HUGIN
Age: 52

Robert J. Hugin has been a director since April 2003. Since May 2006, Mr. Hugin has served as the President and Chief Operating Officer of Celgene Corporation, a biopharmaceutical company focused on cancer and immunological diseases. From June 1999 to May 2006, Mr. Hugin served as the Senior Vice President and Chief Financial Officer of Celgene. From 1985 to 1999, Mr. Hugin held positions with J.P. Morgan & Co. Inc., an investment banking firm, serving most recently as a Managing Director. Mr. Hugin also serves as a director of Celgene Corporation and Coley Pharmaceutical Group, Inc. Mr. Hugin received an A.B. from Princeton University and an M.B.A. from the University of Virginia.

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