EXHIBIT 32.1 CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 In connection with the Quarterly Report of QLT Inc., or the Company, on Form 10-Q for the period ended March 31, 2006 as filed with the Securities and Exchange Commission on the date hereof, or Form 10-Q, I, Robert L. Butchofsky, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that: (1) The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m(a) or 78o(d)); and (2) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: May 9, 2006 /s/ Robert L. Butchofsky -------------------------------------- Robert L.Butchofsky President and Chief Executive Officer QLT Inc. 41