EXHIBIT 99 CERTIFICATION BY CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER TRUSTMARK CORPORATION AND SUBSIDIARIES PURSUANT TO 18 U.S.C. ss. 1350 We, Richard G. Hickson, Chairman of the Board, President & Chief Executive Officer of Trustmark Corporation and Subsidiaries (Trustmark), and Zach L. Wasson, Treasurer of Trustmark, hereby certify that the accompanying report on Form 10-Q (Report) for the period ending June 30, 2002, and filed with the Securities and Exchange Commission on the date hereof pursuant to Section 13(a) of the Securities Exchange Act of 1934 by Trustmark, fully complies with the requirements of that section. We further certify that the information contained in the Report fairly presents, in all material aspects, the financial condition and results of operations of Trustmark. BY: /s/ Richard G. Hickson BY: /s/ Zach L. Wasson ---------------------- ------------------ Richard G. Hickson Zach L. Wasson Chairman of the Board, President Treasurer (Principal & Chief Executive Officer Financial Officer) DATE: August 12, 2002 DATE: August 12, 2002