EXHIBIT 99 CERTIFICATION UNDER SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 The undersigned officers, Wayne M. Fortun, Chief Executive Officer of Hutchinson Technology Incorporated, a Minnesota corporation (the "Company"), and John A. Ingleman, Chief Financial Officer of the Company, hereby certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that: (i) the Quarterly Report on Form 10-Q of the Company for the quarterly period ended March 30, 2003 (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and (ii) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Date: May 12, 2003 /s/ Wayne M. Fortun ------------------------------------- Wayne M. Fortun Chief Executive Officer Date: May 12, 2003 /s/ John A. Ingleman ------------------------------------- John A. Ingleman Chief Financial Officer