**Exhibit 31.1**

 

**Certifications**

 

I, Mark Sieczkarek, certify that:

 

1. I have reviewed thisreport on Form 10-Q of Conceptus, Inc., a Delaware corporation;

 

2. Based on my knowledge,this quarterly 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 my knowledge,the financial statements, and other financial information included in thisreport, fairly present in all material respects, the financial condition,results of operations and cash flows of the registrant as of, and for, theperiods presented in this report;

 

4. The registrant’s other certifying officer 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 registrant and have:

 

a)              designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theregistrant, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which thisreport is being prepared;

 

b)             designed such internal control overfinancial reporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonable assurance regardingthe reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally accepted accountingprinciples;

 

c)              evaluated the effectiveness of theregistrant’s disclosure controls and procedures and presented in this reportour conclusion about the effectiveness of the disclosure controls andprocedures, as or the end of the period covered by this report based on suchevaluation; and

 

d)             disclosed in this report any change inthe registrant’s internal control over financial reporting that occurred duringthe registrant’s most recent fiscal quarter (the registrant’s fourth fiscalquarter in the case of an annual report) that has materially affected, or isreasonably likely to materially affect, the registrant’s internal control overfinancial reporting; and

 

5. The registrant’s othercertifying officer and I have disclosed, based on our most recent evaluation ofinternal control over financial reporting, to the registrant’s auditors and theaudit committee of registrant’s board of directors (or persons performing theequivalent functions):

 

a)              all significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information; and

 

b)             any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theregistrant’s internal control over financial reporting.

 
| Date:  July 29, 2005 |                                   |
|---------------------------|----------------------------------------|
|                      |                                   |
|                      | /s/ Mark  M. Sieczkarek           |
|                      | Mark M.  Sieczkarek                    |
|                      | President  and Chief Executive Officer |

 

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