**Exhibit 31.1**

# **Certifications**

I, Mark Sieczkarek, certify that:

1. I have reviewed this report on Form 10-Q ofConceptus, Inc., a Delaware corporation;

2. Based on my knowledge, this quarterly report doesnot contain any untrue statement of a material fact or omit to state a materialfact necessary to make the statements made, in light of the circumstances underwhich such statements were made, not misleading with respect to the periodcovered by this report;

3. Based on my knowledge, the financial statements,and other financial information included in this report, fairly present in allmaterial respects, the financial condition, results of operations and cashflows of the registrant as of, and for, the periods presented in this report;

4. Theregistrant’s other certifying officer and I are responsible for establishingand maintaining 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 registrant 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 registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period 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 registrant’s disclosure controls and procedures andpresented in this report our conclusion about the effectiveness of thedisclosure controls and procedures, as or the end of the period covered by thisreport based on such evaluation; and

d)             disclosed in thisreport any change in the registrant’s internal control over financial reportingthat occurred during the registrant’s most recent fiscal quarter (theregistrant’s fourth fiscal quarter in the case of an annual report) that hasmaterially affected, or is reasonably likely to materially affect, theregistrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and Ihave disclosed, based on our most recent evaluation of internal control overfinancial reporting, to the registrant’s auditors and the audit committee ofregistrant’s board of directors (or persons performing the equivalentfunctions):

a)              all significantdeficiencies and material weaknesses in the design or operation of internalcontrol over financial reporting which are reasonably likely to adverselyaffect the registrant’s ability to record, process, summarize and reportfinancial information; and

b)             any fraud, whether ornot material, that involves management or other employees who have asignificant role in the registrant’s internal control over financial reporting.

Date: August 9, 2006
|        | /s/ Mark M.  Sieczkarek                |   |
|--------|----------------------------------------|--------|
|   | Mark M.  Sieczkarek                    |
|   | President and Chief  Executive Officer |

 

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