Exhibit 99 HILLS BANCORPORATION CERTIFICATION OF 10-Q FILING JUNE 30, 2002 CERTIFICATION Pursuant to the requirements of Section 906 of the Sarbanes-Oxley Act of 2002, Dwight O. Seegmiller and James G. Pratt certify that: 1. Form 10-Q for the quarterly period ended June 30, 2002 fully complies with the requirements of Sections 13(a) or 15(d) of the 1934 Act, and 2. The information contained in Form 10-Q for the quarterly period ended June 30, 2002 fairly presents, in all material respects, the registrant's financial condition and results of operations of the registrant. August 14, 2002 /s/ Dwight O. Seegmiller - ------------------------ ------------------------------------------ Date Dwight O. Seegmiller, President (Duly authorized office of the registrant) August 14, 2002 /s/ James G. Pratt - ------------------------ ------------------------------------------ Date James G. Pratt, Treasurer (Principal Financial Officer) 1