Certification Pursuant to 18 U.S.C. Section 1350, As Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 Name of Issuer: Van Kampen Investment Grade Municipal Trust In connection with the Report on Form N-CSR (the "Report") of the above-named issuer for the period ended October 31, 2003 that is accompanied by this certification, the undersigned hereby certifies that: 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 Issuer. Date: December 18, 2003 /s/ Ronald E. Robison --------------------------- Ronald E. Robison Principal Executive Officer A signed original of this written statement required by Section 906 has been provided to Van Kampen Investment Grade Municipal Trust and will be retained by Van Kampen Investment Grade Municipal Trust and furnished to the Securities and Exchange Commission or its staff upon request. Certification Pursuant to 18 U.S.C. Section 1350, As Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 Name of Issuer: Van Kampen Investment Grade Municipal Trust In connection with the Report on Form N-CSR (the "Report") of the above-named issuer for the period ended October 31, 2003 that is accompanied by this certification, the undersigned hereby certifies that: 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 Issuer. Date: December 18, 2003 /s/ John L. Sullivan --------------------------- John L. Sullivan Principal Financial Officer A signed original of this written statement required by Section 906 has been provided to Van Kampen Investment Grade Municipal Trust and will be retained by Van Kampen Investment Grade Municipal Trust and furnished to the Securities and Exchange Commission or its staff upon request.