EXHIBIT 32(a)

                      18 U.S.C. SECTION 1350 CERTIFICATIONS

I hereby certify pursuant to 18 U.S.C. ss. 1350, as adopted pursuant to
ss. 906 of the Sarbanes-Oxley Act of 2002, to the best of my knowledge and
belief, that the accompanying Form 10-K of Southwest Bancorp, Inc. ("Southwest")
for the annual period ended December 31, 2005, 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 that the information contained in this Form 10-K
fairly presents, in all material respects, the financial condition and results
of operations of Southwest.

By: /s/ Rick Green                                       March 10, 2006
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Rick Green                                               Date
President and Chief Executive Officer
(Principal Executive Officer)