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EXHIBIT 23.1
CONSENT OF INDEPENDENT AUDITORS
We consent to the reference to our firm under the captions "Selected
Consolidated Financial Data" and "Experts" and to the use of our report dated
April 17, 2000, except for the first and second paragraphs of Note 14, as to
which the date is May 17, 2000, and the third paragraph of Note 14 as to which
the date is June 29, 2000, in Amendment No. 1 to the Registration Statement
(Form S-1, No. 333-37404) and related Prospectus of The Medicines Company for
the registration of 5,000,000 shares of its common stock.
Ernst & Young LLP
Boston, Massachusetts
The foregoing consent is in the form that will be signed upon the completion of
the reverse stock split described in the third paragraph of Note 14 to the
financial statements.
/s/ Ernst & Young LLP
Boston, Massachusetts
June 29, 2000
