International Bancshares (IBOC) 10-Q 2003 Q1 Quarterly report

“Exhibit 99b”

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

In connection with the Quarterly Report of International Bancshares Corporation (the “Company”) on Form 10-Q for the period ended March 31, 2003, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Imelda Navarro, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d), and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

By:	/s/ Imelda Navarro
	Imelda Navarro
	Treasurer
Date:	May 15, 2003