**Exhibit 12.1**

 

***Certificationof the Principal Executive Officer pursuant to §302 of the Sarbanes-Oxley Actof 2002***

 

**Certification**

 

I,Prof. Dr. Juergen Engel, certify that:

 

1.  I have reviewed this annual report on Form 20-Fof Æterna Zentaris Inc.;

 

2.  Basedon my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;

 

3.  Basedon my knowledge, the financial statements, and other financial informationincluded in this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the company as of, and for,the periods presented in this report;

 

4.  Thecompany’s other certifying officer(s) and I are responsible forestablishing and maintaining disclosure controls and procedures (as defined inExchange Act Rules 13a-15(e) and 15d-15(e)) and internal control overfinancial reporting (as defined in Exchange Act Rules 13a-15(f) and15d-15(f)) for the company and have:

 

(a)          Designed suchdisclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that materialinformation relating to the company, including its consolidated subsidiaries,is made known to us by others within those entities, particularly during theperiod in which this report is being prepared;

 

(b)         Designed such internalcontrol over financial reporting, or caused such internal control overfinancial reporting to be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and the preparationof financial statements for external purposes in accordance with generallyaccepted accounting principles;

 

(c)          Evaluated theeffectiveness of the company’s disclosure controls and procedures and presentedin this report our conclusions about the effectiveness of the disclosurecontrols and procedures, as of the end of the period covered by this reportbased on such evaluation; and

 

(d)         Disclosed in thisreport any change in the company’s internal control over financial reportingthat occurred during the period covered by the annual report that hasmaterially affected, or is reasonably likely to materially affect, the company’sinternal control over financial reporting; and

 

5.  Thecompany’s other certifying officer(s) and I have disclosed, based on ourmost recent evaluation of internal control over financial reporting, to thecompany’s auditors and the audit committee of company’s board of directors (orpersons performing the equivalent functions):

 

(a)  All significant deficiencies and material weaknesses in the design oroperation of internal control over financial reporting which are reasonablylikely to adversely affect the company’s ability to record, process, summarizeand report financial information; and

 

(b)  Any fraud, whether or not material, that involves management or otheremployees who have a significant role in the company’s internal control overfinancial reporting.

 

**Date:March 30, 2009**

 
| /s/ Juergen  Engel                     |   |
|----------------------------------------|--------|
|                                   |   |
| Prof.  Dr. Juergen Engel          |   |
| President  and Chief Executive Officer |   |
| (principal  executive officer)         |   |

 

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