EXHIBIT 32.1


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


I, James  Truchard,  certify,  pursuant to 18 U.S.C.  Section  1350,  as adopted
pursuant to Section 906 of the  Sarbanes-Oxley  Act of 2002,  that the Quarterly
Report of National  Instruments  Corporation on Form 10-Q for the fiscal quarter
ended  September 30, 2004 fully complies with the  requirements of Section 13(a)
or 15(d) of the Securities  Exchange Act of 1934 and that information  contained
in such Form  10-Q  fairly  presents  in all  material  respects  the  financial
condition and results of operations of National Instruments Corporation.

                                By: /s/ James Truchard
                              Name: James Truchard
                             Title: Chief Executive Officer

I, Alexander  Davern,  certify,  pursuant to 18 U.S.C.  Section 1350, as adopted
pursuant to Section 906 of the  Sarbanes-Oxley  Act of 2002,  that the Quarterly
Report of National  Instruments  Corporation on Form 10-Q for the fiscal quarter
ended  September 30, 2004 fully complies with the  requirements of Section 13(a)
or 15(d) of the Securities  Exchange Act of 1934 and that information  contained
in such Form  10-Q  fairly  presents  in all  material  respects  the  financial
condition and results of operations of National Instruments Corporation.

                                By: /s/ Alexander Davern
                              Name: Alexander Davern
                             Title: Chief Financial Officer