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 Blackhawk Bancorp, Inc. (the "Company") on Form 10-QSB for the period ended September 30, 2003 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), I, R. Richard Bastian, III, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes- Oxley Act of 2002, that to the best of 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. /s/ R. Richard Bastian, III - ------------------------------------- R. Richard Bastian, III President and Chief Executive Officer November 7, 2003 A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to Blackhawk Bancorp, Inc. and will be retained by Blackhawk Bancorp, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.