Document:

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                                                                   Exhibit 10.07

                              EMPLOYMENT AGREEMENT
                              --------------------

     This Employment Agreement is made as of May 23, 2001, by and between James
R. McNab, Jr. (the "Executive") and Sontra Medical, Inc. (the "Company").

     WHEREAS, the Company desires to employ the Executive, and the Executive
desires to be employed by the Company on the terms specified herein; and

     WHEREAS, the Executive's senior managerial position requires that he be
trusted with extensive confidential information and trade secrets of the Company
and that he develop a thorough and comprehensive knowledge of all details of the
Company's business, including, but not limited to, information relating to
research, development, inventions, purchasing, accounting, marketing,
distribution and licensing of the Company's products and services;

     NOW, THEREFORE, in consideration of the foregoing and the agreements herein
contained, and intending to be legally bound, the parties hereby agree as
follows:

     1. Position and Responsibilities. The Executive agrees to serve as
President and Chairman of the Board of Directors for the Company. The Executive
shall at all times report to, and his activities shall at all times be subject
to the direction and control of the Board of Directors of the Company, and the
Executive shall exercise such powers and comply with and perform, faithfully and
to the best of his ability, such directions and duties in relation to the
business and affairs of the Company as may from time to time be vested in or
requested of him. The Executive shall have such duties as may be assigned to the
Executive from time to time by the Board of Directors.

     2. Term. The parties agree that the Executive's employment with the Company
shall be on an "at-will" basis, which means that either the Executive or the
Company may terminate the employment relationship and this Agreement at any
time, for any or no reason, with or without Cause (as defined below), with or
without prior notice to the other party, but subject to Section 4 hereof.

     3. Compensation and Benefits. As compensation for the satisfactory
performance by the Executive of his duties and obligations hereunder to the
Company and subject to the provisions of Section 4, the Executive shall receive:

          3.1. Base Salary. The Executive's initial salary shall be paid at a
     rate of Ten Thousand Dollars ($10,000) per month (the "Base Salary"). The
     Base Salary shall be payable in accordance with the customary payroll
     practices of the Company as may be established or modified from time to
     time. The Board of Directors in its sole discretion may adjust the
     Executive's salary at any time. All payments shall be subject to all
     applicable federal, state and/or local payroll and withholding taxes.

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          3.2. Benefits. During Executive's employment, and subject to any
     contribution generally required of executives of the Company, the Executive
     shall be eligible to participate in all employee health and benefits plans,
     as may be from time to time adopted by the Company and in effect for
     executives of the Company in similar positions. Executive's participation
     shall be subject to (i) the terms of the applicable plan documents, (ii)
     generally applicable Company policies, and (iii) the discretion of the
     Board or any administrative or other committee provided for in, or
     contemplated by, such plan. In addition, the Executive shall be entitled to
     receive three weeks vacation, which shall be accrued and utilized in
     accordance with the Company's vacation policy/practice as established
     and/or modified from time to time.

     The Company's plans and policies shall govern all other benefits. The
Company and/or the Board of Directors may alter, modify, add to, or delete its
employee benefits plans and policies at any time as the Company and/or the Board
of Directors, in its or their sole judgment, determines to be appropriate.

          3.3. Business Expenses. The Company shall pay or reimburse the
     Executive for all reasonable business expenses incurred or paid by the
     Executive in the performance of his duties and responsibilities hereunder,
     subject to (i) any reasonable expense policy of the Company, as set by the
     Company and/or the Board of Directors from time to time and generally
     applicable to executives of the Company in similar positions, and (ii) such
     reasonable substantiation and documentation requirements as may be
     specified by the Company and/or Board of Directors from time to time.

     4. Termination of Employment. The Executive's employment and this Agreement
shall terminate under the following circumstances:

          4.1. Death or Disability. In the event of the Executive's death or
     Disability (as defined herein) during the Executive's employment hereunder,
     the Executive's employment and this Agreement shall immediately and
     automatically terminate, and the Company shall pay to the Executive (or in
     the case of death, the Executive's designated beneficiary or, if no
     beneficiary has been designated by the Executive, his estate), any Base
     Salary earned but unpaid through the date of death or Disability. For the
     purposes of this Agreement, "Disability" shall mean any physical incapacity
     or mental incompetence (i) as a result of which the Executive is unable to
     perform the essential functions of his job for an aggregate of 90 days,
     whether or not consecutive, during any calendar year, and (ii) which cannot
     be reasonably accommodated by the Company without undue hardship.

          4.2. By the Company for Cause.

               (a) The Company may terminate the Executive's employment and this
          Agreement for Cause at any time. Upon termination for Cause, the
          Company shall have no further obligation or liability to the Executive
          relating to the Executive's employment or this Agreement, other than
          any Base Salary earned but unpaid and accrued but unused vacation
          through the date of termination.

               (b) The following events or conditions shall constitute "Cause"
          for termination of Executive's employment and this Agreement: (i)
          disregard of or failure to follow

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          any written rules or policies of the Company; (ii) failure or refusal
          of the Executive to perform his duties hereunder; (iii) dishonesty,
          embezzlement, misappropriation of assets or property (tangible or
          intangible) of the Company, gross negligence, misconduct, neglect of
          duties, theft, fraud, or breach of fiduciary duty to the Company; (iv)
          violation of federal or state securities laws; (v) breach of an
          employment, consulting or other agreement (including, without
          limitation, the Employee Non-competition, Nondisclosure and
          Developments Agreement between the Executive and the Company); (vi)
          the unauthorized disclosure of any trade secret or confidential
          information of the Company, including confidential information of
          third parties which the Company treats as confidential; (vii) the
          commission of an act which constitutes unfair competition with the
          Company or which induces any customer or supplier to breach a contract
          with the Company; or (viii) the commission of a felony.

               (c) If the Board of Directors, in its sole discretion, determines
          that the reason(s) constituting Cause for termination is subject to
          cure, then the Executive shall be given written notice of the pending
          termination, notice of the action required by the Executive to cure
          the circumstances constituting Cause, and thirty days in which to
          attempt to cure. If in the Board of Directors' determination, the
          reason(s) constituting Cause has been cured, then Executive's
          employment shall not be terminated. If, however, the Board of
          Directors determines, in its sole discretion, that the reason(s) has
          not been cured in the thirty day period, Executive's employment shall
          be subject to immediate termination for Cause.

          4.3 By the Company other than for Cause.

               (a) The Company may terminate the Executive's employment and this
          Agreement other than for Cause at any time. In the event of such
          termination, it is agreed by and between the Company and the Executive
          that they will enter into an independent consulting agreement - the
          terms of which will be subject to negotiation at such time as the
          Executive's employment is terminated under this provision. At a
          minimum, the parties agree that the independent consulting agreement
          will provide for payment of $10,000 per month for consulting services
          for a term of twelve months. Upon execution of an independent
          consulting agreement with Executive, the Company shall have no further
          obligation or liability to the Executive relating to his employment or
          this Agreement, other than any Base Salary earned but unpaid and
          accrued but unused vacation through the date of termination.

               (b) Should the Company elect not to enter into such an
          independent consulting agreement with the Executive, the Executive
          will be entitled to salary continuation at the Base Salary rate for a
          period of six months from the termination date, to be paid in
          accordance with the Company's payroll practice then in effect. If the
          Executive elects to continue medical insurance coverage after the
          termination date in accordance with the provisions of the Consolidated
          Omnibus Reconciliation Act of 1985 ("COBRA"), then the Company shall
          pay his monthly COBRA premium payments for the period of salary
          continuation payments or until he accepts other employment, whichever
          occurs first. The Company shall have no other obligations to the
          Executive upon termination of employment other than for Cause. The
          Company's obligation to provide any of the amounts and benefits
          hereunder shall be subject to, and conditioned upon, the Executive's
          execution of a full release of claims satisfactory to the Company,
          releasing the Company and its employees and agents from any claims
          arising from or

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          related to the Executive's employment or severance from employment
          with the Company, including any claims arising from this Agreement.

               (c) Should the Company and Executive, despite good-faith
          negotiations, fail to reach agreement on a consulting agreement within
          thirty days of Executive's termination from employment, unless the
          thirty day period is otherwise extended in writing by the Company, the
          Company, provided it has offered a consulting agreement specifying
          payment of $10,000 per month for consulting services for a term of
          twelve months, shall have no further obligation or liability to the
          Executive relating to his employment or this Agreement, other than any
          Base Salary earned but unpaid and accrued but unused vacation through
          the date of termination.

          4.4 By the Executive. If the Executive chooses to terminate his
     employment with the Company for any reason other than to transition from
     employment with the Company to an independent consultant relationship with
     the Company, the Company shall have no further obligation or liability to
     the Executive relating to the Executive's employment or this Agreement,
     other than for Base Salary earned but unpaid and accrued but unused
     vacation through the date of termination. In the event the Executive
     terminates his employment to transition to an independent consulting
     relationship with the Company, the provisions of Section 4.3 shall apply
     with respect to the Company's obligation to negotiate and enter into an
     independent consulting agreement with Executive.

         5. Effect of Termination. The provisions of this Section 5 shall apply
in the event of termination of this Agreement and/or the Executive's employment
pursuant to Section 4.

          5.1. Payment in Full. Payment by the Company to the Executive of any
     Base Salary and other compensation amounts as specified in Section 4.2
     (upon termination for Cause) and Sections 4.3 and 4.4, as well as
     fulfillment of the Company's obligation to negotiate in good-faith with
     Executive for an independent consulting agreement pursuant to Section 4.3,
     shall constitute the entire obligation of the Company to the Executive,
     except that nothing in this Section 5.1 is intended or shall be construed
     to affect the rights and obligations of the Company, on the one hand, and
     the Executive, on the other, with respect to any loans, stock warrants,
     stock pledge arrangements, option plans or other agreements to the extent
     said rights or obligations survive the Executive's termination of
     employment under the provisions of documents relating thereto.

          5.2. Termination of Benefits. Except for any right of continuation of
     benefits coverage to the extent provided by this Agreement and/or COBRA, or
     other applicable law, benefits shall terminate pursuant to the terms of the
     applicable benefit plans as of the termination date of the Executive's
     employment.

          5.3 Cessation of Severance and Benefits. If the Executive breaches his
     obligations under this Agreement and/or the Non-competition, Nondisclosure
     and Developments Agreement, the Company may immediately cease payment of
     all severance and benefits described in this Agreement. The cessation of
     these payments shall be in addition to, and not as an alternative to, any
     other remedies at law or in equity available to the Company, including the
     right to seek specific performance or an injunction.

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     6. Non-competition, Nondisclosure and Developments Obligations. As a
condition of the Company entering into this Agreement, the Employee agrees to
execute, prior to the execution of this Agreement by the Company, the Company's
Employee Non-competition, Nondisclosure and Developments Agreement (the
"Nondisclosure Agreement") attached hereto as Exhibit A. The obligations of the
Executive under the Nondisclosure Agreement expressly survive any termination of
the Executive's employment, regardless of the manner of such termination, or
termination of this Agreement.

     7. Conflicting Agreements. The Executive hereby warrants that the execution
of this Agreement and the performance of his obligations hereunder will not
breach or be in conflict with any other agreement to which or by which the
Executive is a party or is bound and that the Executive is not now subject to
and will not enter into any agreement, including, without limitation, any
covenants against competition or similar covenants that would affect the
performance of his obligations hereunder.

     8. Withholding; Taxes. All payments made by the Company under this
Agreement shall be subject to and reduced by any federal, state and/or local
taxes or other amounts required to be withheld by the Company under any
applicable law.

     9. Miscellaneous.

          9.1. Assignment. The Executive shall not assign this Agreement or any
     interest herein. The Company may assign this Agreement, and it is
     specifically understood and agreed that no such assignment by the Company
     shall be deemed to be a "termination" of the Executive's employment with
     the Company within the meaning of Section 4 hereof. This Agreement shall
     inure to the benefit of the Company and shall be binding upon the Company
     and the Executive, and their respective successors, executors,
     administrators, heirs and permitted assigns.

          9.2. Severability. If any portion or provision of this Agreement shall
     to any extent be declared illegal or unenforceable by a court of competent
     jurisdiction, then the application of such provision in such circumstances
     shall be modified to permit its enforcement to the maximum extent permitted
     by law, and both the application of such portion or provision in
     circumstances other than those as to which it is so declared illegal or
     unenforceable and the remainder of this Agreement shall not be affected
     thereby, and each portion and provision of this Agreement shall be valid
     and enforceable to the fullest extent permitted by law.

          9.3. Waiver; Amendment. No waiver of any provision hereof shall be
     effective unless made in writing and signed by the waiving party. The
     failure of the Company to require the performance of any term or obligation
     of this Agreement, or the waiver by the Company of any breach of this
     Agreement, shall not prevent any subsequent enforcement of such term or
     obligation or be deemed a waiver of any subsequent breach. This Agreement
     may be amended or modified only by a written instrument signed by the
     Executive and/or an authorized member of the Board of Directors.

          9.4. Notices. All notices, requests and other communications provided
     for by this Agreement shall be in writing and shall be effective when
     delivered in person or three (3)

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     business days after being deposited in the mail of the United States,
     postage prepaid, registered or certified, and addressed (a) in the case of
     the Executive, to the address set forth underneath his signature to this
     Agreement or (b) in the case of the Company, to the attention of the
     Chairman of the Board, at 58 Charles Street, Cambridge, Massachusetts,
     02141, and/or to such other address as either party may specify by notice
     to the other.

          9.5. Entire Agreement. This Agreement and the Non-competition,
     Nondisclosure and Developments Agreement constitute the entire agreement
     between the Company and the Executive with respect to the terms and
     conditions of the Executive's employment with the Company and supersede all
     prior communications, agreements and understandings, written or oral,
     between the Executive and the Company with respect to the terms and
     conditions of the Executive's employment with the Company.

          9.6. Counterparts. This Agreement may be executed in counterparts,
     each of which shall be original and all of which together shall constitute
     one and the same instrument.

          9.7. Governing Law. This Agreement, the employment relationship
     contemplated herein and any claim arising from such relationship, whether
     or not arising under this Agreement, shall be governed by and construed in
     accordance with the internal laws of the Commonwealth of Massachusetts
     without giving effect to any choice or conflict of laws provision or rule
     thereof.

          9.8. Consent to Jurisdiction. Each of the Company and the Executive,
     by its or his execution hereof, hereby irrevocably submits to the exclusive
     jurisdiction of the state or federal courts of the Commonwealth of
     Massachusetts for the purpose of any claim or action arising out of or
     based upon this Agreement, the Executive's employment with the Company
     and/or termination thereof, or relating to the subject matter hereof, and
     agrees not to commence any such claim or action other than in the
     above-named courts.

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     IN WITNESS WHEREOF, this Agreement has been executed by the Company, by its
duly authorized representative, and by the Executive, as of the date first above
written.

                                  SONTRA MEDICAL, INC.

                                  By:  /s/ Joseph Kost
                                       -----------------------------------------
                                  Name: Joseph Kost
                                        ----------------------------------------
                                  Title: Chief Scientific Officer
                                        ----------------------------------------

                                  THE EXECUTIVE

                                  /s/ James R. McNab, Jr.
                                  ----------------------------------------------
                                  Signature

                                      James R. McNab, Jr.
                                  ----------------------------------------------
                                  Name - please print

                                  ADDRESS:

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                                                                   Exhibit 10.08

                              EMPLOYMENT AGREEMENT

          This Employment Agreement is made as of June 12, 2001, by and between
Joseph Kost (the "Employee") and Sontra Medical, Inc. (the "Company").

          WHEREAS, the Company desires to employ the Employee, and the Employee
desires to be employed by the Company on the terms specified herein; and

          WHEREAS, the Employee's senior managerial position requires that he be
trusted with extensive confidential information and trade secrets of the Company
and that he develop a thorough and comprehensive knowledge of all details of the
Company's business, including, but not limited to, information relating to
research, development, inventions, purchasing, accounting, marketing,
distribution and licensing of the Company's products and services;

          NOW, THEREFORE, in consideration of the foregoing and the agreements
herein contained, and intending to be legally bound, the parties hereby agree as
follows:

          1.   Position and Responsibilities. The Employee agrees to serve as
Chief Scientific Officer of the Company. The Employee shall at all times report
to, and his activities shall at all times be subject to the direction and
control of the President and Chief Executive Officer ("CEO") and/or the Board of
Directors of the Company, and the Employee shall exercise such powers and comply
with and perform, faithfully and to the best of his ability, such directions and
duties in relation to the business and affairs of the Company as may from time
to time be vested in or requested of him. The Employee shall have such duties as
may be assigned to the Employee from time to time by the President and CEO
and/or Board of Directors. The Company understands that the Employee currently
maintains and will continue to maintain an appointment as a professor on the
faculty of Ben-Gurion University of Israel.

          2.   Term. The parties agree that the Employee's employment with the
Company shall be on an "at-will" basis, which means that either the Employee or
the Company may terminate the employment relationship and this Agreement at any
time, for any or no reason, with or without Cause (as defined below), with or
without prior notice to the other party, but subject to Section 4 hereof.

          3.   Compensation and Benefits. As compensation for the satisfactory
performance by the Employee of his duties and obligations hereunder to the
Company and subject to the provisions of Section 4, the Employee shall receive:

               3.1.  Base Salary. The Employee's initial salary shall be paid at
a rate of Sixteen Thousand, Six Hundred and Sixty Six Dollars and Sixty-Seven
Cents ($16,666.67) per month (the "Base Salary"). The Base Salary shall be
payable in accordance with the customary payroll practices of the Company as may
be established or modified from time to time. The Board of Directors in its sole
discretion may adjust the Employee's salary at any time. All

<PAGE>

payments shall be subject to all applicable federal, state and/or local payroll
and withholding taxes.

               3.2.  Benefits. During Employee's employment, and subject to any
contribution generally required of employees of the Company, the Employee shall
be eligible to participate in all employee health and benefits plans, as may be
from time to time adopted by the Company and in effect for employees of the
Company in similar positions. Employee's participation shall be subject to (i)
the terms of the applicable plan documents, (ii) generally applicable Company
policies, and (iii) the discretion of the Board or any administrative or other
committee provided for in, or contemplated by, such plan. In addition, the
Employee shall be entitled to receive three weeks vacation, which shall be
accrued and utilized in accordance with the Company's vacation policy/practice
as established and/or modified from time to time.

          The Company's plans and policies shall govern all other benefits. The
Company and/or the Board of Directors may alter, modify, add to, or delete its
employee benefits plans and policies at any time as the Company and/or the Board
of Directors, in its or their sole judgment, determines to be appropriate.

               3.3.  Business Expenses. The Company shall pay or reimburse the
Employee for all reasonable business expenses incurred or paid by the Employee
in the performance of his duties and responsibilities hereunder, subject to (i)
any reasonable expense policy of the Company, as set by the Company and/or the
Board of Directors from time to time and generally applicable to employees of
the Company in similar positions, and (ii) such reasonable substantiation and
documentation requirements as may be specified by the Company and/or Board of
Directors from time to time.

          4.   Termination of Employment. The Employee's employment and this
Agreement shall terminate under the following circumstances:

               4.1.  Death or Disability. In the event of the Employee's death
or Disability (as defined herein) during the Employee's employment hereunder,
the Employee's employment and this Agreement shall immediately and automatically
terminate, and the Company shall pay to the Employee (or in the case of death,
the Employee's designated beneficiary or, if no beneficiary has been designated
by the Employee, his estate), any Base Salary earned but unpaid through the date
of death or Disability. For the purposes of this Agreement, "Disability" shall
mean any physical incapacity or mental incompetence (i) as a result of which the
Employee is unable to perform the essential functions of his job for an
aggregate of 90 days, whether or not consecutive, during any calendar year, and
(ii) which cannot be reasonably accommodated by the Company without undue
hardship.

               4.2.  By the Company for Cause.

                     (a) The Company may terminate the Employee's employment
and this Agreement for Cause at any time. Upon termination for Cause, the
Company shall have no further obligation or liability to the Employee relating
to the Employee's employment or this Agreement, other than any Base Salary
earned but unpaid and accrued but unused vacation through the date of
termination.

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                     (b) The following events or conditions shall constitute
"Cause" for termination of Employee's employment and this Agreement: (i)
disregard of or failure to follow any written rules or policies of the Company;
(ii) failure or refusal of the Employee to perform his duties hereunder; (iii)
dishonesty, embezzlement, misappropriation of assets or property (tangible or
intangible) of the Company, gross negligence, misconduct, neglect of duties,
theft, fraud, or breach of fiduciary duty to the Company; (iv) violation of
federal or state securities laws; (v) breach of an employment, consulting or
other agreement (including, without limitation, the Employee Non-competition,
Nondisclosure and Developments Agreement between the Employee and the Company);
(vi) the unauthorized disclosure of any trade secret or confidential information
of the Company, including confidential information of third parties which the
Company treats as confidential; (vii) the commission of an act which constitutes
unfair competition with the Company or which induces any customer or supplier to
breach a contract with the Company; or (viii) the commission of a felony.

                     (c) If the Board of Directors, in its sole discretion,
determines that the reason(s) constituting Cause for termination is subject to
cure, then the Employee shall be given written notice of the pending
termination, notice of the action required by the Employee to cure the
circumstances constituting Cause, and thirty days in which to attempt to cure.
If in the Board of Directors' determination, the reason(s) constituting Cause
has been cured, then Employee's employment shall not be terminated. If, however,
the Board of Directors determines, in its sole discretion, that the reason(s)
has not been cured in the thirty day period, Employee's employment shall be
subject to immediate termination for Cause.

               4.3   By the Company other than for Cause.

                     (a) The Company may terminate the Employee's employment
and this Agreement other than for Cause at any time. In the event of such
termination, it is agreed by and between the Company and the Employee that they
will enter into an independent consulting agreement - the terms of which will be
subject to negotiation at such time as the Employee's employment is terminated
under this provision. At a minimum, the parties agree that the independent
consulting agreement will provide for payment of $10,000.00 per month for
consulting services for a term of twelve months. Upon execution of an
independent consulting agreement with Employee, the Company shall have no
further obligation or liability to the Employee relating to his employment or
this Agreement, other than any Base Salary earned but unpaid and accrued but
unused vacation through the date of termination.

                     (b) Should the Company elect not to enter into such an
independent consulting agreement with the Employee, the Employee will be
entitled to salary continuation at the Base Salary rate for a period of six
months from the termination date, to be paid in accordance with the Company's
payroll practice then in effect. If the Employee elects to continue medical
insurance coverage after the termination date in accordance with the provisions
of the Consolidated Omnibus Reconciliation Act of 1985 ("COBRA"), then the
Company shall pay his monthly COBRA premium payments for the period of salary
continuation payments or until he accepts other employment, whichever occurs
first. The Company shall have no other obligations to the Employee upon
termination of employment other than for Cause. The Company's obligation to
provide any of the amounts and benefits hereunder shall be subject to, and
conditioned upon, the Employee's execution of a full release of claims
satisfactory to the

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Company, releasing the Company and its employees and agents from any claims
arising from or related to the Employee's employment or severance from
employment with the Company, including any claims arising from this Agreement.

                     (c) Should the Company and Employee, despite good-faith
negotiations, fail to reach agreement on a consulting agreement within thirty
days of Employee's termination from employment, unless the thirty day period is
otherwise extended in writing by the Company, the Company, provided it has
offered a consulting agreement specifying payment of $10,000.00 per month for
consulting services for a term of twelve months, shall have no further
obligation or liability to the Employee relating to his employment or this
agreement, other than any Base Salary earned but unpaid and accrued but unused
vacation through the date of termination.

               4.4   By the Employee. If the Employee chooses to terminate his
employment with the Company for any reason other than to transition from
employment with the Company to an independent consultant relationship with the
Company, the Company shall have no further obligation or liability to the
Employee relating to the Employee's employment or this Agreement, other than for
Base Salary earned but unpaid and accrued but unused vacation through the date
of termination. In the event the Employee terminates his employment to
transition to an independent consulting relationship with the Company, the
provisions of Section 4.3 shall apply with respect to the Company's obligation
to negotiate and enter into an independent consulting agreement with Employee.

          5.   Effect of Termination. The provisions of this Section 5 shall
apply in the event of termination of this Agreement and/or the Employee's
employment pursuant to Section 4.

               5.1.  Payment in Full. Payment by the Company to the Employee of
any Base Salary and other compensation amounts as specified in Section 4.2 (upon
termination for Cause) and Sections 4.3 and 4.4, as well as fulfillment of the
Company's obligation to negotiate in good-faith with Employee for an independent
consulting agreement pursuant to Section 4.3, shall constitute the entire
obligation of the Company to the Employee, except that nothing in this Section
5.1 is intended or shall be construed to affect the rights and obligations of
the Company, on the one hand, and the Employee, on the other, with respect to
any loans, stock warrants, stock pledge arrangements, option plans or other
agreements to the extent said rights or obligations survive the Employee's
termination of employment under the provisions of documents relating thereto.

               5.2.  Termination of Benefits. Except for any right of
continuation of benefits coverage to the extent provided by this Agreement
and/or COBRA, or other applicable law, benefits shall terminate pursuant to the
terms of the applicable benefit plans as of the termination date of the
Employee's employment.

               5.3   Cessation of Severance and Benefits. If the Employee
breaches his obligations under this Agreement and/or the Non-competition,
Nondisclosure and Developments Agreement, the Company may immediately cease
payment of all severance and benefits described in this Agreement. The cessation
of these payments shall be in addition to, and not as

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an alternative to, any other remedies at law or in equity available to the
Company, including the right to seek specific performance or an injunction.

          6.   Non-competition, Nondisclosure and Developments Obligations. As a
condition of the Company entering into this Agreement, the Employee agrees to
execute, prior to the execution of this Agreement by the Company, the Company's
Employee Non-competition, Nondisclosure and Developments Agreement (the
"Nondisclosure Agreement") attached hereto as Exhibit A. The obligations of the
Employee under the Nondisclosure Agreement expressly survive any termination of
the Employee's employment, regardless of the manner of such termination, or
termination of this Agreement.

          7.   Withholding; Taxes. All payments made by the Company under this
Agreement shall be subject to and reduced by any federal, state and/or local
taxes or other amounts required to be withheld by the Company under any
applicable law.

          8.   Miscellaneous.

               8.1.  Assignment. The Employee shall not assign this Agreement or
any interest herein. The Company may assign this Agreement, and it is
specifically understood and agreed that no such assignment by the Company shall
be deemed to be a "termination" of the Employee's employment with the Company
within the meaning of Section 4 hereof. This Agreement shall inure to the
benefit of the Company and shall be binding upon the Company and the Employee,
and their respective successors, executors, administrators, heirs and permitted
assigns.

               8.2.  Severability. If any portion or provision of this Agreement
shall to any extent be declared illegal or unenforceable by a court of competent
jurisdiction, then the application of such provision in such circumstances shall
be modified to permit its enforcement to the maximum extent permitted by law,
and both the application of such portion or provision in circumstances other
than those as to which it is so declared illegal or unenforceable and the
remainder of this Agreement shall not be affected thereby, and each portion and
provision of this Agreement shall be valid and enforceable to the fullest extent
permitted by law.

               8.3.  Waiver; Amendment. No waiver of any provision hereof shall
be effective unless made in writing and signed by the waiving party. The failure
of the Company to require the performance of any term or obligation of this
Agreement, or the waiver by the Company of any breach of this Agreement, shall
not prevent any subsequent enforcement of such term or obligation or be deemed a
waiver of any subsequent breach. This Agreement may be amended or modified only
by a written instrument signed by the Employee and/or an authorized member of
the Board of Directors.

               8.4.  Notices. All notices, requests and other communications
provided for by this Agreement shall be in writing and shall be effective when
delivered in person or three (3) business days after being deposited in the mail
of the United States, postage prepaid, registered or certified, and addressed
(a) in the case of the Employee, to the address set forth underneath his
signature to this Agreement or (b) in the case of the Company, to the attention
of the Chairman

                                       -5-

<PAGE>

of the Board, at 58 Charles Street, Cambridge, Massachusetts, 02141, and/or to
such other address as either party may specify by notice to the other.

               8.5.  Entire Agreement. This Agreement and the Non-competition,
Nondisclosure and Developments Agreement constitute the entire agreement between
the Company and the Employee with respect to the terms and conditions of the
Employee's employment with the Company and supersede all prior communications,
agreements and understandings, written or oral, between the Employee and the
Company with respect to the terms and conditions of the Employee's employment
with the Company.

               8.6.  Counterparts. This Agreement may be executed in
counterparts, each of which shall be original and all of which together shall
constitute one and the same instrument.

               8.7.  Governing Law. This Agreement, the employment relationship
contemplated herein and any claim arising from such relationship, whether or not
arising under this Agreement, shall be governed by and construed in accordance
with the internal laws of the Commonwealth of Massachusetts without giving
effect to any choice or conflict of laws provision or rule thereof.

               8.8.  Consent to Jurisdiction. Each of the Company and the
Employee, by its or his execution hereof, hereby irrevocably submits to the
exclusive jurisdiction of the state or federal courts of the Commonwealth of
Massachusetts for the purpose of any claim or action arising out of or based
upon this Agreement, the Employee's employment with the Company and/or
termination thereof, or relating to the subject matter hereof, and agrees not to
commence any such claim or action other than in the above-named courts.

                                       -6-

<PAGE>

          IN WITNESS WHEREOF, this Agreement has been executed by the Company,
by its duly authorized representative, and by the Employee, as of the date first
above written.

                                     SONTRA MEDICAL, INC.

                                     By:/s/ James R. McNab, Jr.
                                        ----------------------------------------

                                     Name: James R. McNab, Jr.
                                           -------------------------------------

                                     Title: Chairman and Chief Executive Officer
                                            ------------------------------------

                                     THE EMPLOYEE

                                     /s/ Joseph Kost
                                     -------------------------------------------
                                     Signature

                                     Joseph Kost
                                     Name - please print

                                     ADDRESS:

                                       -7-

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