**Exhibit 12.1**

 

***Certification of the PrincipalExecutive Officer pursuant to §302 of the Sarbanes-Oxley Act of 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 and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the company and have:

 

(a)          Designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision, toensure that material information relating to the company, including itsconsolidated subsidiaries, is made known to us by others within those entities,particularly during the period in which this report is being prepared;

 

(b)         Designed such internal control over financial reporting, or caused suchinternal control over financial reporting to be designed under our supervision,to provide reasonable assurance regarding the reliability of financialreporting and the preparation of financial statements for external purposes inaccordance with generally accepted accounting principles;

 

(c)          Evaluated the effectiveness of the company’s disclosure controls andprocedures and presented in this report our conclusions about the effectivenessof the disclosure controls and procedures, as of the end of the period coveredby this report based on such evaluation; and

 

(d)         Disclosed in this report any change in the company’s internal controlover financial reporting that occurred during the period covered by the annualreport that has materially affected, or is reasonably likely to materiallyaffect, the company’s internal control over financial reporting; and

 

5.  Thecompany’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to thecompany’s auditors and the audit committee of the company’s board of directors(or persons 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, 2010**

 

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

 

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