Electro Scientific Industries (ESIO) 10-Q 2004 Q3 Quarterly report

EXHIBIT 32.1

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

In connection with this quarterly report on Form 10-Q of Electro Scientific Industries, Inc. (the “Company”) for the quarterly period ended November 29, 2003 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Barry L. Harmon, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(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/ Barry L. Harmon

Barry L. Harmon

President and Chief Executive Officer

January 6, 2004