Old Second Bancorp (OSBC) 10-Q 2011 Q1 Quarterly 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 Quarterly Report of Old Second Bancorp, Inc. (the “Company”) on Form 10-Q for the period ending March 31, 2011 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, William B Skoglund, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

(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 result of operations of the Company.

	/s/ William B. Skoglund
	William B. Skoglund
	Chairman of the Board, Director President and Chief Executive Officer (principal executive officer)
May 10, 2011