EXHIBIT 32.1

CERTIFICATIONS PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Certification of Principal Executive Officer

In connection with the report of UnitedHealth Group Incorporated (the “Company”) on Form 10-K for the period ended December 31, 2012 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Stephen J. Hemsley, certify pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that to my 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.

February 6, 2013	/s/    STEPHEN J. HEMSLEY
	Stephen J. Hemsley President and Chief Executive Officer

Certification of Principal Financial Officer

In connection with the report of UnitedHealth Group Incorporated (the “Company”) on Form 10-K for the period ended December 31, 2012 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David S. Wichmann, certify pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that to my 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.

February 6, 2013	/s/    DAVID S. WICHMANN
	David S. Wichmann Executive Vice President and Chief Financial Officer of UnitedHealth Group and President of UnitedHealth Group Operations