Exhibit 99.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION
906 OF THE SABARNES-OXLEY ACT OF 2002

In connection with the Annual Report of Discovery Partners International, Inc. (the “Company”) on Form 10-K for the period ended December 31, 2002 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Riccardo Pigliucci, 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:

(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/ Riccardo Pigliucci

Riccardo Pigliucci
Chief Executive Officer

Date: March 19, 2003