<PAGE>

           As filed with the Securities and Exchange Commission on July 15, 2002
                                                      Registration No. 333-54618
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

                                   ----------

                           Sontra Medical Corporation
             (Exact Name of Registrant as specified in its charter)


<TABLE>
<S>                                                                        <C>
                          Minnesota                                                     41-1649949
(State or other jurisdiction of incorporation or organization)             (I.R.S. Employer Identification No.)
</TABLE>

                                58 Charles Street
                               Cambridge, MA 02141
               (Address of Principal Executive Offices) (Zip Code)

                           ---------------------------


                 1997 Long-Term Incentive and Stock Option Plan
            Sontra Medical, Inc. 1999 Stock Option and Incentive Plan
                            (Full title of the plan)

                           ---------------------------

                                Thomas W. Davison
                             Chief Executive Officer
                           Sontra Medical Corporation
                                58 Charles Street
                               Cambridge, MA 02141
               (Name and Address of Agent for Service of Process)

                                 (617) 494-5337
          (Telephone Number, Including Area Code, of Agent For Service)

                           ---------------------------

                                    Copy to:

                          Lawrence S. Wittenberg, Esq.
                         Testa, Hurwitz & Thibeault, LLP
                                 125 High Street
                           Boston, Massachusetts 02110
                                 (617) 248-7000

================================================================================

<PAGE>


                         CALCULATION OF REGISTRATION FEE

================================================================================

<TABLE>
<CAPTION>
                                                                        Proposed
                                                                         Maximum          Proposed
                                                                        Offering           Maximum
Title of Securities                                  Amount to be      Price Per         Aggregate           Amount of
to be Registered                                  Registered/(1)/          Share    Offering Price    Registration Fee
----------------------------------------------------------------------------------------------------------------------
<S>                                                 <C>                <C>          <C>               <C>
Common Stock, $.01 par value /(2)/                      421,404            $3.68         $1,550,767               $143

Common Stock, $.01 par value /(3)/                      142,858            $1.05         $  150,001               $ 14
                                                         66,666            $2.25         $  149,999               $ 14
                                                         63,158            $2.38         $  150,316               $ 14
                                                        200,000            $2.50         $  500,000               $ 46
                                                        359,914            $3.05         $1,097,738               $101
                                                        150,000            $3.30         $  495,000               $ 46
                                                         10,000            $3.38         $   33,800               $  3
                                                         46,000            $3.75         $  172,500               $ 16
                                                         40,000            $4.25         $  170,000               $ 16

Common Stock, $.01 par value /(4)/                      340,086            $3.74         $1,271,922               $117
                                                        526,453            $0.52         $  273,756               $ 25
                                               -----------------------------------------------------------------------

                  Total                               2,366,539                          $6,015,799               $553
----------------------------------------------------------------------------------------------------------------------
</TABLE>


/(1)/  In addition, pursuant to Rule 416(a), this Registration Statement also
       covers such indeterminate number of additional shares of Common Stock as
       is necessary to eliminate any dilutive effect of any future stock split,
       stock dividend or similar transaction.

/(2)/  Consists of shares issuable under the Registrant's 1997 Long-Term
       Incentive and Stock Option Plan. Pursuant to Rule 457(h), the aggregate
       offering price and the fee have been computed upon the basis of the
       average of the high and low reported price of the Common Stock of the
       Registrant on the Nasdaq SmallCap Market on July 11, 2002.

/(3)/  Such shares are issuable upon exercise of outstanding options with fixed
       exercise prices under the Registrant's 1997 Long-Term Incentive and Stock
       Option Plan. Pursuant to Rule 457(h), the aggregate offering price and
       the fee have been computed upon the basis of the price at which the
       options may be exercised. The offering price per share set forth for such
       shares is the exercise price per share at which such options are
       exercisable.

/(4)/  Such shares are issuable upon exercise of outstanding options with fixed
       exercise prices under the Sontra Medical, Inc. 1999 Stock Option and
       Incentive Plan. Pursuant to Rule 457(h), the aggregate offering price and
       the fee have been computed upon the basis of the price at which the
       options may be exercised. The offering price per share set forth for such
       shares is the exercise price per share at which such options are
       exercisable.

                                       -2-

<PAGE>

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.

         The documents containing the information specified in this Item 1 will
be sent or given to employees, directors or others as specified by Rule
428(b)(1). In accordance with the rules and regulations of the Securities and
Exchange Commission (the "Commission") and the instructions to Form S-8, such
documents are not being filed with the Commission either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Rule 424.

Item 2.  Registrant Information and Employee Plan Annual Information.

         The documents containing the information specified in this Item 2 will
be sent or given to employees, directors or others as specified by Rule 428(b).
In accordance with the rules and regulations of the Commission and the
instructions to Form S-8, such documents are not being filed with the Commission
either as part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

         The following documents filed with the Commission are incorporated by
reference in this Registration Statement:

(a)      The Registrant's Annual Report on Form 10-KSB for the fiscal year ended
         December 31, 2001 filed pursuant to Section 13(a) or 15(d) of the
         Securities Exchange Act of 1934, as amended (the "Exchange Act");

(b)      All other reports filed pursuant to Section 13(a) or 15(d) of the
         Exchange Act since the end of the fiscal year covered by the
         Registrant's document referred to in (a) above.

(c)      The section entitled "Description of Registrant's Securities to be
         Registered" contained in the Registrant's Registration Statement on
         Form 8-A, filed pursuant to Section 12(g) of the Exchange Act on
         November 12, 1997, and incorporating by reference the information
         contained in the Registrant's Registration Statement on Form SB-2
         (Registration No. 333-29969).

         All documents subsequently filed with the Commission by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part thereof from the date of filing of such documents.

                                       -3-

<PAGE>

Item 4.  Description of Securities.

         Not applicable.


Item 5.  Interests of Named Experts and Counsel.

         Not applicable.


Item 6.  Indemnification of Directors and Officers.

         Section 302A.521 of the Minnesota Business Corporation Act provides
that unless prohibited or limited by a corporation's articles of incorporation
or bylaws, the Company must indemnify its current and former officers,
directors, employees and agents against reasonable expenses (including
attorneys' fees), judgments, penalties, fines and amounts paid in settlement and
which were incurred in connection with actions, suits, or proceedings in which
such persons are parties by reason of the fact that they are or were an officer,
director, employee or agent of the corporation, if they (i) have not been
indemnified by another organization, (ii) acted in good faith, (iii) received no
improper personal benefit, (iv) in the case of a criminal proceeding, had no
reasonable cause to believe the conduct was unlawful, and (v) reasonably
believed that the conduct was in the best interests of the corporation. Section
302A.521 also permits a corporation to purchase and maintain insurance on behalf
of its officers, directors, employees and agents against any liability which may
be asserted against, or incurred by, such persons in their capacities as
officers, directors, employees and agents of the corporation, whether or not the
corporation would have been required to indemnify the person against the
liability under the provisions of such section.

         Article Sixth of the Registrant's Amended and Restated Articles of
Incorporation, as amended, eliminates the personal liability of directors to the
Registrant or its stockholders for monetary damages for breaches of their
fiduciary duty to the fullest extent permitted by the Minnesota Business
Corporation Act. Article VII of the Registrant's Bylaws provides that the
directors, officers and committee members of the Company and other persons shall
have the rights to indemnification provided by Section 302A.521 of the Minnesota
Business Corporation Act. In addition, the Registrant has an existing directors
and officers liability insurance policy.

         The effect of these provisions would be to permit such indemnification
by the Registrant for liabilities arising under the Securities Act of 1933, as
amended, to the extent permitted under such act.

Item 7.  Exemption From Registration Claimed.

         Not applicable.

                                       -4-

<PAGE>

Item 8.  Exhibits.

   Exhibit No.                              Description of Exhibit

   5.1                 Opinion of Testa, Hurwitz & Thibeault, LLP

   23.1                Consent of Schechter Dokken Kanter Andrews & Selcer, Ltd.

   23.2*               Consent of Arthur Andersen LLP (omitted pursuant to Rule
                       437(a))

   23.3                Consent of Testa, Hurwitz & Thibeault, LLP (included in
                       Exhibit 5.1)

   24.1                Power of Attorney (included as part of the signature page
                       of this Registration Statement)


*        After reasonable efforts, we have not been able to obtain the consent
         of Arthur Andersen LLP to the incorporation into this Registration
         Statement on Form S-8, of their report with respect to our financial
         statements, which appeared in our Registration Statement on Form S-4/A
         as filed with the Securities and Exchange Commission on May 16, 2002.
         Under these circumstances, Rule 437(a) under the Securities Act of
         1933, as amended, permits this Registration Statement to be filed
         without a written consent from Arthur Andersen. Because Arthur Andersen
         has not consented to the incorporation by reference of their report
         into this Registration Statement, you will not be able to assert claims
         against Arthur Andersen under Section 11 of the Securities Act of 1933,
         as amended, for any untrue statement of a material fact contained in
         our financial statements incorporated herein or any omissions to state
         a material fact required to be stated therein.

Item 9.  Undertakings.

         (a)      The undersigned registrant hereby undertakes:

                  (1)    To file, during any period in which offers or sales are
                  being made, a post-effective amendment to this Registration
                  Statement (unless the information required by paragraphs (i)
                  and (ii) below is contained in periodic reports filed by the
                  Registrant pursuant to Section 13 or Section 15(d) of the
                  Exchange Act that are incorporated by reference in this
                  Registration Statement):

                         (i)    To include any prospectus required by Section
                         10(a)(3) of the Securities Act;

                         (ii)   To reflect in the prospectus any facts or events
                         which, individually or together, represent a
                         fundamental change in the information set forth in this
                         Registration Statement. Notwithstanding the foregoing,
                         any increase or decrease in volume of securities
                         offered (if the total dollar value of securities
                         offered would not exceed that which was registered) and
                         any deviation from the low or high end of the estimated
                         maximum offering range may be reflected in the form of
                         prospectus filed with the Commission pursuant to Rule
                         424(b) if, in the aggregate, the changes in volume and
                         price represent no more than a 20 percent change in the
                         maximum aggregate offering price set forth in the
                         "Calculation of Registration Fee" table in the
                         effective Registration Statement; and

                                       -5-

<PAGE>

                         (iii)  To include any additional or changed material
                         information with respect to the plan of distribution.

                  (2)    For determining liability under the Securities Act, to
                  treat each post-effective amendment as a new registration
                  statement of the securities offered, and the offering of the
                  securities at that time to be the initial bona fide offering.

                  (3)    To file a post-effective amendment to remove from
                  registration any of the securities that remain unsold at the
                  end of the offering.

                                       -6-

<PAGE>

Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Cambridge, in the Commonwealth of Massachusetts, on
this 15th day of July, 2002.

                                        SONTRA MEDICAL CORPORATION

                                        By: /s/ Thomas W. Davison
                                           -------------------------------------
                                           Thomas W. Davison
July 15, 2002                              Chief Executive Officer

                        POWER OF ATTORNEY AND SIGNATURES

         We, the undersigned officers and directors of Sontra Medical
Corporation, hereby severally constitute and appoint Thomas W. Davison and Sean
Moran, and each of them singly, our true and lawful attorneys, with full power
to them and each of them singly, to sign for us in our names in the capacities
indicated below, all pre-effective and post-effective amendments to this
Registration Statement and any related subsequent registration statement
pursuant to Rule 462(b) of the Securities Act of 1933, as amended, and generally
to do all things in our names and on our behalf in such capacities to enable
Sontra Medical Corporation to comply with the provisions of the Securities Act
of 1933, as amended, and all requirements of the Securities and Exchange
Commission.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons on behalf of the
registrant in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
             SIGNATURE                                       TITLE                                  DATE
<S>                                   <C>                                                       <C>
/s/ James R. McNab, Jr.               Chairman of the Board and Director                        July 15, 2002
-------------------------------------
James R. McNab, Jr.

/s/ Thomas W. Davison                 President, Chief Executive Officer and                    July 15, 2002
-------------------------------------
Thomas W. Davison                     Director (Principal Executive Officer)

/s/ Sean Moran                        Chief Financial Officer                                   July 15, 2002
-------------------------------------
Sean Moran                            (Principal Financial and Accounting Officer)

/s/ Joseph Kost                       Chief Scientific Officer and Director                     July 15, 2002
-------------------------------------
Joseph Kost

/s/ Robert S. Langer                  Director                                                  July 15, 2002
-------------------------------------
Robert S. Langer

/s/ Martin P. Sutter                  Director                                                  July 11, 2002
-------------------------------------
Martin P. Sutter

/s/ W. Leigh Thompson                 Director                                                  July 11, 2002
-------------------------------------
W. Leigh Thompson

/s/ Gary S. Kohler                    Director                                                  July 15, 2002
-------------------------------------
Gary S. Kohler

/s/ Michael Wigley                    Director                                                  July 11, 2002
-------------------------------------
Michael Wigley
</TABLE>

                                       -7-

<PAGE>

                               INDEX TO EXHIBITS

Exhibit No.        Description of Exhibit

5.1                Opinion of Testa, Hurwitz & Thibeault, LLP

23.1               Consent of Schechter Dokken Kanter Andrews & Selcer, Ltd.

23.2*              Consent of Arthur Andersen LLP (omitted pursuant to Rule
                   437(a))

23.3               Consent of Testa, Hurwitz & Thibeault, LLP (included in
                   Exhibit 5.1)

24.1               Power of Attorney (included as part of the signature page of
                   this Registration Statement)



*        After reasonable efforts, we have not been able to obtain the consent
         of Arthur Andersen LLP to the incorporation into this Registration
         Statement on Form S-8, of their report with respect to our financial
         statements, which appeared in our Registration Statement on Form S-4/A
         as filed with the Securities and Exchange Commission on May 16, 2002.
         Under these circumstances, Rule 437(a) under the Securities Act of
         1933, as amended, permits this Registration Statement to be filed
         without a written consent from Arthur Andersen. Because Arthur Andersen
         has not consented to the incorporation by reference of their report
         into this Registration Statement, you will not be able to assert claims
         against Arthur Andersen under Section 11 of the Securities Act of 1933,
         as amended, for any untrue statement of a material fact contained in
         our financial statements incorporated herein or any omissions to state
         a material fact required to be stated therein.

                                       -8-
[{"type": "S-8", "sequence": "1", "filename": "ds8.txt", "description": "FORM S-8", "secsgml_size_bytes": 21861}]
{"company-data": {"conformed-name": "SONTRA MEDICAL CORP", "cik": "0001031927", "assigned-sic": "3845", "irs-number": "411649949", "state-of-incorporation": "MN", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-92414", "film-number": "02703348"}, "business-address": {"street1": "58 CHARLES STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02141", "phone": "6174945337"}, "mail-address": {"street1": "58 CHARLES STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02141"}, "former-company": [{"former-conformed-name": "INTELLIPHONE INC", "date-changed": "19970625"}, {"former-conformed-name": "CHOICETEL COMMUNICATIONS INC /MN/", "date-changed": "19970625"}, {"former-conformed-name": "SONTRA MEDICAL CORP", "date-changed": "20020701"}, {"former-conformed-name": "CHOICETEL COMMUNICATIONS INC/MN/", "date-changed": "20020701"}]}
As filed with the Securities and Exchange Commission on July 15, 2002
                                                      Registration No. 333-54618
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

                                   ----------

                           Sontra Medical Corporation
             (Exact Name of Registrant as specified in its charter)
Minnesota                                                     41-1649949
(State or other jurisdiction of incorporation or organization)             (I.R.S. Employer Identification No.)
58 Charles Street
                               Cambridge, MA 02141
               (Address of Principal Executive Offices) (Zip Code)

                           ---------------------------

                 1997 Long-Term Incentive and Stock Option Plan
            Sontra Medical, Inc. 1999 Stock Option and Incentive Plan
                            (Full title of the plan)

                           ---------------------------

                                Thomas W. Davison
                             Chief Executive Officer
                           Sontra Medical Corporation
                                58 Charles Street
                               Cambridge, MA 02141
               (Name and Address of Agent for Service of Process)

                                 (617) 494-5337
          (Telephone Number, Including Area Code, of Agent For Service)

                           ---------------------------

                                    Copy to:

                          Lawrence S. Wittenberg, Esq.
                         Testa, Hurwitz & Thibeault, LLP
                                 125 High Street
                           Boston, Massachusetts 02110
                                 (617) 248-7000

================================================================================
CALCULATION OF REGISTRATION FEE

================================================================================
Proposed
                                                                         Maximum          Proposed
                                                                        Offering           Maximum
Title of Securities                                  Amount to be      Price Per         Aggregate           Amount of
to be Registered                                  Registered/(1)/          Share    Offering Price    Registration Fee
----------------------------------------------------------------------------------------------------------------------
Common Stock, $.01 par value /(2)/                      421,404            $3.68         $1,550,767               $143

Common Stock, $.01 par value /(3)/                      142,858            $1.05         $  150,001               $ 14
                                                         66,666            $2.25         $  149,999               $ 14
                                                         63,158            $2.38         $  150,316               $ 14
                                                        200,000            $2.50         $  500,000               $ 46
                                                        359,914            $3.05         $1,097,738               $101
                                                        150,000            $3.30         $  495,000               $ 46
                                                         10,000            $3.38         $   33,800               $  3
                                                         46,000            $3.75         $  172,500               $ 16
                                                         40,000            $4.25         $  170,000               $ 16

Common Stock, $.01 par value /(4)/                      340,086            $3.74         $1,271,922               $117
                                                        526,453            $0.52         $  273,756               $ 25
                                               -----------------------------------------------------------------------

                  Total                               2,366,539                          $6,015,799               $553
----------------------------------------------------------------------------------------------------------------------
/(1)/  In addition, pursuant to Rule 416(a), this Registration Statement also
       covers such indeterminate number of additional shares of Common Stock as
       is necessary to eliminate any dilutive effect of any future stock split,
       stock dividend or similar transaction.

/(2)/  Consists of shares issuable under the Registrant's 1997 Long-Term
       Incentive and Stock Option Plan. Pursuant to Rule 457(h), the aggregate
       offering price and the fee have been computed upon the basis of the
       average of the high and low reported price of the Common Stock of the
       Registrant on the Nasdaq SmallCap Market on July 11, 2002.

/(3)/  Such shares are issuable upon exercise of outstanding options with fixed
       exercise prices under the Registrant's 1997 Long-Term Incentive and Stock
       Option Plan. Pursuant to Rule 457(h), the aggregate offering price and
       the fee have been computed upon the basis of the price at which the
       options may be exercised. The offering price per share set forth for such
       shares is the exercise price per share at which such options are
       exercisable.

/(4)/  Such shares are issuable upon exercise of outstanding options with fixed
       exercise prices under the Sontra Medical, Inc. 1999 Stock Option and
       Incentive Plan. Pursuant to Rule 457(h), the aggregate offering price and
       the fee have been computed upon the basis of the price at which the
       options may be exercised. The offering price per share set forth for such
       shares is the exercise price per share at which such options are
       exercisable.

                                       -2-
PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.

         The documents containing the information specified in this Item 1 will
be sent or given to employees, directors or others as specified by Rule
428(b)(1). In accordance with the rules and regulations of the Securities and
Exchange Commission (the "Commission") and the instructions to Form S-8, such
documents are not being filed with the Commission either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Rule 424.

Item 2.  Registrant Information and Employee Plan Annual Information.

         The documents containing the information specified in this Item 2 will
be sent or given to employees, directors or others as specified by Rule 428(b).
In accordance with the rules and regulations of the Commission and the
instructions to Form S-8, such documents are not being filed with the Commission
either as part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

         The following documents filed with the Commission are incorporated by
reference in this Registration Statement:

(a)      The Registrant's Annual Report on Form 10-KSB for the fiscal year ended
         December 31, 2001 filed pursuant to Section 13(a) or 15(d) of the
         Securities Exchange Act of 1934, as amended (the "Exchange Act");

(b)      All other reports filed pursuant to Section 13(a) or 15(d) of the
         Exchange Act since the end of the fiscal year covered by the
         Registrant's document referred to in (a) above.

(c)      The section entitled "Description of Registrant's Securities to be
         Registered" contained in the Registrant's Registration Statement on
         Form 8-A, filed pursuant to Section 12(g) of the Exchange Act on
         November 12, 1997, and incorporating by reference the information
         contained in the Registrant's Registration Statement on Form SB-2
         (Registration No. 333-29969).

         All documents subsequently filed with the Commission by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part thereof from the date of filing of such documents.

                                       -3-
Item 4.  Description of Securities.

         Not applicable.

Item 5.  Interests of Named Experts and Counsel.

         Not applicable.

Item 6.  Indemnification of Directors and Officers.

         Section 302A.521 of the Minnesota Business Corporation Act provides
that unless prohibited or limited by a corporation's articles of incorporation
or bylaws, the Company must indemnify its current and former officers,
directors, employees and agents against reasonable expenses (including
attorneys' fees), judgments, penalties, fines and amounts paid in settlement and
which were incurred in connection with actions, suits, or proceedings in which
such persons are parties by reason of the fact that they are or were an officer,
director, employee or agent of the corporation, if they (i) have not been
indemnified by another organization, (ii) acted in good faith, (iii) received no
improper personal benefit, (iv) in the case of a criminal proceeding, had no
reasonable cause to believe the conduct was unlawful, and (v) reasonably
believed that the conduct was in the best interests of the corporation. Section
302A.521 also permits a corporation to purchase and maintain insurance on behalf
of its officers, directors, employees and agents against any liability which may
be asserted against, or incurred by, such persons in their capacities as
officers, directors, employees and agents of the corporation, whether or not the
corporation would have been required to indemnify the person against the
liability under the provisions of such section.

         Article Sixth of the Registrant's Amended and Restated Articles of
Incorporation, as amended, eliminates the personal liability of directors to the
Registrant or its stockholders for monetary damages for breaches of their
fiduciary duty to the fullest extent permitted by the Minnesota Business
Corporation Act. Article VII of the Registrant's Bylaws provides that the
directors, officers and committee members of the Company and other persons shall
have the rights to indemnification provided by Section 302A.521 of the Minnesota
Business Corporation Act. In addition, the Registrant has an existing directors
and officers liability insurance policy.

         The effect of these provisions would be to permit such indemnification
by the Registrant for liabilities arising under the Securities Act of 1933, as
amended, to the extent permitted under such act.

Item 7.  Exemption From Registration Claimed.

         Not applicable.

                                       -4-
Item 8.  Exhibits.

   Exhibit No.                              Description of Exhibit

   5.1                 Opinion of Testa, Hurwitz & Thibeault, LLP

   23.1                Consent of Schechter Dokken Kanter Andrews & Selcer, Ltd.

   23.2*               Consent of Arthur Andersen LLP (omitted pursuant to Rule
                       437(a))

   23.3                Consent of Testa, Hurwitz & Thibeault, LLP (included in
                       Exhibit 5.1)

   24.1                Power of Attorney (included as part of the signature page
                       of this Registration Statement)

*        After reasonable efforts, we have not been able to obtain the consent
         of Arthur Andersen LLP to the incorporation into this Registration
         Statement on Form S-8, of their report with respect to our financial
         statements, which appeared in our Registration Statement on Form S-4/A
         as filed with the Securities and Exchange Commission on May 16, 2002.
         Under these circumstances, Rule 437(a) under the Securities Act of
         1933, as amended, permits this Registration Statement to be filed
         without a written consent from Arthur Andersen. Because Arthur Andersen
         has not consented to the incorporation by reference of their report
         into this Registration Statement, you will not be able to assert claims
         against Arthur Andersen under Section 11 of the Securities Act of 1933,
         as amended, for any untrue statement of a material fact contained in
         our financial statements incorporated herein or any omissions to state
         a material fact required to be stated therein.

Item 9.  Undertakings.

         (a)      The undersigned registrant hereby undertakes:

                  (1)    To file, during any period in which offers or sales are
                  being made, a post-effective amendment to this Registration
                  Statement (unless the information required by paragraphs (i)
                  and (ii) below is contained in periodic reports filed by the
                  Registrant pursuant to Section 13 or Section 15(d) of the
                  Exchange Act that are incorporated by reference in this
                  Registration Statement):

                         (i)    To include any prospectus required by Section
                         10(a)(3) of the Securities Act;

                         (ii)   To reflect in the prospectus any facts or events
                         which, individually or together, represent a
                         fundamental change in the information set forth in this
                         Registration Statement. Notwithstanding the foregoing,
                         any increase or decrease in volume of securities
                         offered (if the total dollar value of securities
                         offered would not exceed that which was registered) and
                         any deviation from the low or high end of the estimated
                         maximum offering range may be reflected in the form of
                         prospectus filed with the Commission pursuant to Rule
                         424(b) if, in the aggregate, the changes in volume and
                         price represent no more than a 20 percent change in the
                         maximum aggregate offering price set forth in the
                         "Calculation of Registration Fee" table in the
                         effective Registration Statement; and

                                       -5-
(iii)  To include any additional or changed material
                         information with respect to the plan of distribution.

                  (2)    For determining liability under the Securities Act, to
                  treat each post-effective amendment as a new registration
                  statement of the securities offered, and the offering of the
                  securities at that time to be the initial bona fide offering.

                  (3)    To file a post-effective amendment to remove from
                  registration any of the securities that remain unsold at the
                  end of the offering.

                                       -6-
Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Cambridge, in the Commonwealth of Massachusetts, on
this 15th day of July, 2002.

                                        SONTRA MEDICAL CORPORATION

                                        By: /s/ Thomas W. Davison
                                           -------------------------------------
                                           Thomas W. Davison
July 15, 2002                              Chief Executive Officer

                        POWER OF ATTORNEY AND SIGNATURES

         We, the undersigned officers and directors of Sontra Medical
Corporation, hereby severally constitute and appoint Thomas W. Davison and Sean
Moran, and each of them singly, our true and lawful attorneys, with full power
to them and each of them singly, to sign for us in our names in the capacities
indicated below, all pre-effective and post-effective amendments to this
Registration Statement and any related subsequent registration statement
pursuant to Rule 462(b) of the Securities Act of 1933, as amended, and generally
to do all things in our names and on our behalf in such capacities to enable
Sontra Medical Corporation to comply with the provisions of the Securities Act
of 1933, as amended, and all requirements of the Securities and Exchange
Commission.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons on behalf of the
registrant in the capacities and on the dates indicated.
SIGNATURE                                       TITLE                                  DATE
/s/ James R. McNab, Jr.               Chairman of the Board and Director                        July 15, 2002
-------------------------------------
James R. McNab, Jr.

/s/ Thomas W. Davison                 President, Chief Executive Officer and                    July 15, 2002
-------------------------------------
Thomas W. Davison                     Director (Principal Executive Officer)

/s/ Sean Moran                        Chief Financial Officer                                   July 15, 2002
-------------------------------------
Sean Moran                            (Principal Financial and Accounting Officer)

/s/ Joseph Kost                       Chief Scientific Officer and Director                     July 15, 2002
-------------------------------------
Joseph Kost

/s/ Robert S. Langer                  Director                                                  July 15, 2002
-------------------------------------
Robert S. Langer

/s/ Martin P. Sutter                  Director                                                  July 11, 2002
-------------------------------------
Martin P. Sutter

/s/ W. Leigh Thompson                 Director                                                  July 11, 2002
-------------------------------------
W. Leigh Thompson

/s/ Gary S. Kohler                    Director                                                  July 15, 2002
-------------------------------------
Gary S. Kohler

/s/ Michael Wigley                    Director                                                  July 11, 2002
-------------------------------------
Michael Wigley
-7-
INDEX TO EXHIBITS

Exhibit No.        Description of Exhibit

5.1                Opinion of Testa, Hurwitz & Thibeault, LLP

23.1               Consent of Schechter Dokken Kanter Andrews & Selcer, Ltd.

23.2*              Consent of Arthur Andersen LLP (omitted pursuant to Rule
                   437(a))

23.3               Consent of Testa, Hurwitz & Thibeault, LLP (included in
                   Exhibit 5.1)

24.1               Power of Attorney (included as part of the signature page of
                   this Registration Statement)

*        After reasonable efforts, we have not been able to obtain the consent
         of Arthur Andersen LLP to the incorporation into this Registration
         Statement on Form S-8, of their report with respect to our financial
         statements, which appeared in our Registration Statement on Form S-4/A
         as filed with the Securities and Exchange Commission on May 16, 2002.
         Under these circumstances, Rule 437(a) under the Securities Act of
         1933, as amended, permits this Registration Statement to be filed
         without a written consent from Arthur Andersen. Because Arthur Andersen
         has not consented to the incorporation by reference of their report
         into this Registration Statement, you will not be able to assert claims
         against Arthur Andersen under Section 11 of the Securities Act of 1933,
         as amended, for any untrue statement of a material fact contained in
         our financial statements incorporated herein or any omissions to state
         a material fact required to be stated therein.

                                       -8-