MedAssets (MDAS) 10-K 2011 FY Annual report

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the annual report of MedAssets, Inc. (the “Company”) on Form 10-K for the year ended December 31, 2011 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, in the capacities and on the dates indicated below, each hereby certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that, to the best of their knowledge:

1. The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/    John A. Bardis

John A. Bardis

Chairman, President and Chief Executive Officer

February 27, 2012

/s/    Charles O. Garner

Charles O. Garner

Executive Vice President, Chief Financial Officer

February 27, 2012

This certification accompanies the Report pursuant to § 906 of the Sarbanes-Oxley Act of 2002, and shall not, except to the extent required by the Sarbanes-Oxley Act of 2002, be deemed filed by the Company for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended.

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.