Exhibit 99.1 CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 I, Nandan M. Nilekani, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly Report of Infosys Technologies Limited on Form 6-K for the quarterly period ended December 31, 2002 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Quarterly Report on Form 6-K fairly presents in all material respects the financial condition and results of operations of Infosys Technologies Limited. By: /s/ Nandan M. Nilekani ---------------------------------------- Nandan M. Nilekani, Chief Executive Officer I, T.V. Mohandas Pai, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly Report of Infosys Technologies Limited on Form 6-K for the quarterly period ended December 31, 2002 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Quarterly Report on Form 6-K fairly presents in all material respects the financial condition and results of operations of Infosys Technologies Limited. By: /s/ T.V. Mohandas Pai -------------------------------------------- T.V. Mohandas Pai, Chief Financial Officer