**Exhibit 12.1**

 

**Certification of Chief Executive Officer**

 

I, Ronald H.P. Brus, certify that:

 

1.                       I havereviewed this annual report on Form 20-F of Crucell N.V.;

 

2.                       Based on myknowledge, this report does not contain any untrue statement of a material factor omit to state a material fact necessary to make the statements made, inlight of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;

 

3.                       Based on myknowledge, the financial statements, and other financial information includedin 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 establishing andmaintaining disclosure controls and procedures (as defined in Exchange ActRules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act Rules 13a-15(f) and 15d-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 suchinternal control 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 report basedon such evaluation; and

 

d)                     Disclosed in thisreport any changes 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, thecompany’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)                      Allsignificant deficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likely toadversely affect the company’s ability to record, process, summarize and reportfinancial information; and

 

b)                      Any fraud,whether or not material, that involves management or other employees who have asignificant role in the company’s internal control over financial reporting.

 

Date:  April 21, 2009

 

 
|   | By:                            | /s/ Ronald H.P. Brus |   |
|--------|--------------------------------|----------------------|--------|
|   | Name: Ronald H.P. Brus         |
|   | Title: Chief Executive Officer |