EXHIBIT 31.3
CERTIFICATIONS
I, Clive A. Meanwell, certify that:
1. I have reviewed this report on Form 10-Q/A of The Medicines Company;
2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.
/s/ Clive A. Meanwell
Clive A. Meanwell
Chairman and Chief Executive Officer
Dated: July 24, 2013
