Exhibit 31a  Certification  I, Dennis E. Nixon, certify that:  1.I have reviewed
this Annual Report on Form 10-K of International Bancshares Corporation; 2.Based on my
knowledge, this report does not contain any untrue statement of a material fact
or omit to state a material fact necessary to make the statements made, in
light of the circumstances under which such statements were made, not
misleading with respect to the period covered by this report; 3.Based on my
knowledge, the financial statements, and other financial information included
in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the registrant as of, and
for, the periods presented in this report; 4.The registrants
other certifying officer and I are responsible for establishing and maintaining
disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and
15d-15(e)) and internal control over financial reporting (as defined in
Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and
have: a.Designed such disclosure
controls and procedures, or caused such disclosure controls and procedures to
be designed under our supervision, to ensure that material information relating
to the registrant, including its consolidated subsidiaries, is made known to us
by others within those entities, particularly during the period in which this
report is being prepared; b.Designed such internal
control over financial reporting, or caused such internal control over financial
reporting to be designed under our supervision, to provide reasonable assurance
regarding the reliability of financial reporting and the preparation of
financial statements for external purposes in accordance with generally
accepted accounting principles; c.Evaluated the effectiveness
of the registrants disclosure controls and procedures and presented in this
report our conclusions about the effectiveness of the disclosure controls and
procedures, as of the end the period covered by this report based on such
evaluation; and d.Disclosed in this report any
change in the registrants internal control over financial reporting that
occurred during the registrants most recent fiscal quarter (the registrants
fourth fiscal quarter in the case of an annual report) that has materially
affected, or is reasonably likely to materially affect, the registrants
internal control over financial reporting; and 5.The registrants
other certifying officer and I have disclosed, based on our most recent
evaluation of internal control over financial reporting, to the registrants
auditors and the audit committee of the registrants board of directors (or
persons performing the equivalent functions): a.All significant deficiencies
and material weaknesses in the design or operation of internal control over
financial reporting which are reasonably likely to adversely affect the
registrants ability to record, process, summarize and report financial
information; and b.Any fraud, whether or not
material, that involves management or other employees who have a significant
role in the registrants internal control over financial reporting.   Date:
  February 25,
  2009By:
  /s/
  Dennis E. NixonDennis
  E. NixonPresident
  (Chief Executive Officer)