Exhibit 31.1

CERTIFICATION

I, Thomas W. Davison, President and Chief Executive Officer of Sontra Medical Corporation, certify
that:

1. I have reviewed this quarterly report on Form 10-QSB of Sontra Medical Corporation;

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

3. Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the small business issuer as of, and for, the periods presented in this report.

4. The small business issuers other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the small business issuer and have:

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

(b) Evaluated the effectiveness of the small business issuers disclosure
controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(c) Disclosed in this report any change in the small business issuers internal control over financial reporting that occurred during the small business
issuers most recent fiscal quarter (the small business issuers fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the small business issuers internal
control over financial reporting; and

5. The small business issuers other certifying officer and I have disclosed, based on our most recent
evaluation of internal control over financial reporting, to the small business issuers auditors and the audit committee of the small business issuers board of directors (or persons performing the equivalent function):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely
affect the small business issuers ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not
material, that involves management or other employees who have a significant role in the small business issuers internal control over financial reporting.

Date: August 11, 2006



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|/s/ Thomas W. Davison                                  
|Thomas W. Davison President and Chief Executive Officer