EX-32.1 4 a07-8459_1ex32d1.htm CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER PURSUANT TO SECTION 906 OF SARBANES-OXLEY ACT OF 2002

EXHIBIT 32.1

CERTIFICATION 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 Annual Report of Æterna Zentaris Inc. (the “Company”) on Form 40-F for the year ended December 31, 2006 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Gilles Gagnon, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, 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 Company.

Dated: March 23, 2007

Gilles Gagnon

President and Chief Executive Officer