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                                                                 Exhibit 10.2.57


                              EMPLOYMENT AGREEMENT


         This Employment Agreement is made and entered into effective as of
April 1, 2000 ("Effective Date), by and between NEOPROBE CORPORATION, a Delaware
Corporation with a place of business at 425 Metro Place North, Suite 300,
Dublin, Ohio 43017-1367 (the "Company") and BRENT LARSON of Dublin, Ohio (the
"Employee").

         WHEREAS, the Company and the Employee wish to establish terms,
covenants, and conditions for the Employee's continued employment with the
Company through this agreement ("Employment Agreement").

         NOW, THEREFORE, in consideration of the mutual agreements herein set
forth, the parties hereto agree as follows:

1.       DUTIES. From and after the Effective Date, and based upon the terms and
         conditions set forth herein, the Company agrees to employ the Employee
         and the Employee agrees to be employed by the Company, as Vice-
         President, Finance and Chief Financial Officer, in such equivalent,
         additional or higher level position or positions as shall be assigned
         to him by the Chief Executive Officer of the Company. While serving in
         such position, the Employee shall report to, be responsible to, and
         shall take direction from the Chief Executive Officer of the Company.
         During the Term of this Employment Agreement (as defined in Section 2
         below), the Employee agrees to devote substantially all of his time to
         the position he holds with the Company and to faithfully,
         industriously, and to the best of his ability, experience and talent,
         perform the duties which are assigned to him. The Employee shall
         observe and abide by the reasonable corporate policies and decisions of
         the Company in all business matters.

2.       TERM OF THIS EMPLOYMENT AGREEMENT. Subject to Sections 4 and 5 hereof,
         the Term of this Employment Agreement shall be for an initial period of
         eighteen (18) months commencing April 1, 2000 and terminating September
         30, 2001.

3.       COMPENSATION. During the Term of this Employment Agreement, the Company
         shall pay, and the Employee agrees to accept as full consideration for
         the services to be rendered by the Employee hereunder, compensation
         consisting of the following:

         A.       SALARY. Beginning on the first day of the Term of this
                  Employment Agreement, the Company shall pay the Employee a
                  salary of One Hundred Thirty Thousand Dollars ($130,000) per
                  year, payable in semi-monthly or monthly installments.

         B.       BONUS. The Compensation Committee of the Company will, on an
                  annual basis, review the performance of the Employee and the
                  Company will pay such bonus as it deems appropriate, in its
                  discretion, to the Employee based upon such review. Such
                  review and bonus shall be consistent with any bonus plan
                  adopted by the Compensation Committee which covers the
                  executive officers of the Company generally.

         C.       BENEFITS. During the Term of this Employment Agreement, the
                  Employee will receive such employee benefits as are generally
                  available to all employees of the Company.

         D.       STOCK OPTIONS. The Compensation Committee of the Board of
                  Directors may, from time-to-time, grant stock options,
                  restricted stock purchase opportunities and such other forms
                  of stock-based incentive compensation as it deems appropriate,
                  in its discretion, to the Employee under the Company's Stock
                  Option and Restricted Stock Purchase Plan and the 1996 Stock
                  Incentive Plan (the "Stock Plans"). The terms of the relevant
                  award agreements shall govern the rights of the Employee and
                  the Company thereunder in the event of any conflict between
                  such agreement and this Employment Agreement.

         E.       VACATION. The Employee shall be entitled to twenty (20) days
                  of vacation during each calendar year
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                  during the Term of this Employment Agreement.

         F.       EXPENSES. The Company shall reimburse the Employee for all
                  reasonable out-of-pocket expenses incurred by him in the
                  performance of his duties hereunder, including expenses for
                  travel, entertainment and similar items, promptly after the
                  presentation by the Employee, from time-to-time, of an
                  itemized account of such expenses.

4.       TERMINATION.

         A.       FOR CAUSE. The Company may terminate the employment of the
                  Employee prior to the end of the Term of this Employment
                  Agreement for cause. In the event of termination by the
                  Company "for cause," all salary, benefits and other payments
                  shall cease at the time of termination, and the Company shall
                  have no further obligations to the Employee.

         B.       RESIGNATION. If the Employee resigns for any reason, all
                  salary, benefits and other payments (except as otherwise
                  provided in paragraph G of this Section 4 below) shall cease
                  at the time such resignation become effective. At the time of
                  any such resignation, the Company shall pay the Employee the
                  value of any accrued but unused vacation time, and the amount
                  of all accrued but previously unpaid base salary through the
                  date of such termination. The Company shall promptly reimburse
                  the Employee for the amount of any expenses incurred prior to
                  such termination by the Employee as required under paragraph F
                  of Section 3 above.

         C.       DISABILITY, DEATH. The Company may terminate the employment of
                  the Employee prior to the end of the Term of this Employment
                  Agreement if the Employee has been unable to perform his
                  duties hereunder for a continuous period of six (6) months due
                  to a physical or mental condition that, in the opinion of a
                  licensed physician, will be of indefinite duration or is
                  without a reasonable probability of recovery. The Employee
                  agrees to submit to an examination by a licensed physician in
                  order to obtain such opinion at the request of the Company.
                  Such examination shall be paid for by the Company and shall be
                  performed by a licensed physician designated by the Company.
                  However, this provision does not abrogate either the Company's
                  or the Employee's rights and obligations pursuant to the
                  Family and Medical Leave Act of 1993, and a termination of
                  employment under this paragraph C shall not be deemed to be a
                  termination for cause.

                  If during the Term of this Employment Agreement, the Employee
                  dies or his employment is terminated because of his
                  disability, all salary, benefits and other payments shall
                  cease at the time of death or disability. At the time of any
                  such termination, the Company shall pay the Employee, the
                  value of any accrued but unused vacation time, and the amount
                  of all accrued but previously unpaid base salary through the
                  date of such termination. The Company shall promptly reimburse
                  the Employee for the amount of any expenses incurred prior to
                  such termination by the Employee as required under paragraph F
                  of Section 3 above.

         D.       TERMINATION WITHOUT CAUSE. A termination without cause is a
                  termination of the employment of the Employee by the Company
                  that is not "for cause" and not occasioned by the resignation,
                  death or disability of the Employee. If the Company terminates
                  the employment of the Employee without cause, (whether before
                  the end of the Term of this Employment Agreement or, if the
                  Employee is employed by the Company under paragraph E of this
                  Section 4 above, after the Term of this Employment Agreement
                  has ended) the Company shall, at the time of such termination,
                  pay to the Employee the severance payment provided in
                  paragraph F of this Section 4 below together with the value of
                  any accrued but unused vacation time and the amount of all
                  accrued but previously unpaid base salary through the date of
                  such termination and shall provide him with all of this
                  benefits under paragraph C of Section 3 above for the full
                  unexpired Term of this Employment Agreement. The Company shall
                  promptly reimburse the Employee for the amount of any expenses
                  incurred prior to such termination by the Employee as required
                  under paragraph F of Section 3 above.

                  If the Company terminates the employment of the Employee
                  because it has ceased to do business or substantially
                  completed the liquidation of its assets or because it has
                  relocated to another city and the
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                  Employee has decided not to relocate also, such termination of
                  employment shall be deemed to be without cause.

         E.       END OF THE TERM OF THIS EMPLOYMENT AGREEMENT. Except as
                  otherwise provided in paragraphs F and G of this Section 4
                  below, the Company may terminate the employment of the
                  Employee at the end of the Term of this Employment Agreement
                  without any liability on the part of the Company to the
                  Employee but, if the Employee continues to be an employee of
                  the Company after the Term of this Employment Agreement ends,
                  his employment shall be governed by the terms and conditions
                  of this Agreement, but he shall be an employee at will and his
                  employment may be terminated at any time by either the Company
                  or the Employee without notice and for any reason not
                  prohibited by law or no reason at all. If the Company
                  terminates the employment of the Employee at the end of the
                  Term of this Employment Agreement, the Company shall, at the
                  time of such termination, pay to the Employee the severance
                  payment provided in paragraph F of this Section 4 below
                  together with the value of any accrued but unused vacation
                  time and the amount of all accrued but previously unpaid base
                  salary through the date of such termination. The Company shall
                  promptly reimburse the Employee for the amount of any expenses
                  incurred prior to such termination by the Employee as required
                  under paragraph F of Section 3 above.

         F.       SEVERANCE. If the employment of the Employee is terminated by
                  the Company, at the end of the Term of this Employment
                  Agreement or, without cause (whether before the end of the
                  Term of this Employment Agreement or, if the Employee is
                  employed by the Company under paragraph E of this Section 4
                  above, after the Term of this Employment Agreement has ended),
                  the Employee shall be paid, as a severance payment at the time
                  of such termination, the amount of One Hundred Forty Thousand
                  Eight Hundred Thirty-Three Dollars ($140,833). If any such
                  termination occurs at or after the substantial completion of
                  the liquidation of the assets of the Company, the severance
                  payment shall be increased by adding Thirty-Two Thousand Five
                  Hundred Dollars ($32,500) to such amount.

         G.       CHANGE OF CONTROL SEVERANCE. In addition to the rights of the
                  Employee under the Company's employee benefit plans
                  (paragraphs C of Section 3 above) but in lieu of any severance
                  payment under paragraph F of this Section 4 above, if there is
                  a Change in Control of the Company (as defined below) and the
                  employment of the Employee is concurrently or subsequently
                  terminated (a) by the Company without cause, (b) by the
                  expiration of the Term of this Employment Agreement, or (c) by
                  the resignation of the Employee because he has reasonably
                  determined in good faith that his titles, authorities,
                  responsibilities, salary, bonus opportunities or benefits have
                  been materially diminished, that a material adverse change in
                  his working conditions has occurred, that his services are no
                  longer required in light of the Company's business plan, or
                  the Company has breached this Employment Agreement, the
                  Company shall pay the Employee, as a severance payment, at the
                  time of such termination, the amount of One Hundred
                  Ninety-Five Thousand Dollars ($195,000) together with the
                  value of any accrued but unused vacation time, and the amount
                  of all accrued but previously unpaid base salary through the
                  date of termination and shall provide him with all of this
                  benefits under paragraph C of Section 3 above for the longer
                  of six (6) months or the full unexpired Term of this
                  Employment Agreement. If any such termination occurs at or
                  after the substantial completion of the liquidation of the
                  assets of the Company, the severance payment shall be
                  increased by adding Thirty-Two Thousand Five Hundred Dollars
                  ($32,500) to such amount. The Company shall promptly reimburse
                  the Employee for the amount of any expenses incurred prior to
                  such termination by the Employee as required under paragraph F
                  of Section 3 above.

                  For the purpose of this Employment Agreement, a Change in
                  Control of the Company has occurred when: (a) any person
                  (defined for the purposes of this paragraph G to mean any
                  person within the meaning of Section 13 (d) of the Securities
                  Exchange Act of 1934 (the "Exchange Act")), other than
                  Neoprobe or an employee benefit plan created by its Board of
                  Directors for the benefit of its employees, either directly or
                  indirectly, acquires beneficial ownership (determined under
                  Rule 13d-3 of the Regulations promulgated by the Securities
                  and Exchange Commission under Section 13(d) of the Exchange
                  Act) of securities issued by Neoprobe having fifteen percent
                  (15%) or more of the voting power of all the voting securities
                  issued by Neoprobe in the election of Directors at the next
                  meeting of the holders of voting securities to be held for
                  such purpose; (b) a majority of the
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                  Directors elected at any meeting of the holders of voting
                  securities of Neoprobe are persons who were not nominated for
                  such election by the Board of Directors or a duly constituted
                  committee of the Board of Directors having authority in such
                  matters; (c) the stockholders of Neoprobe approve a merger or
                  consolidation of Neoprobe with another person other than a
                  merger or consolidation in which the holders of Neoprobe's
                  voting securities issued and outstanding immediately before
                  such merger or consolidation continue to hold voting
                  securities in the surviving or resulting corporation (in the
                  same relative proportions to each other as existed before such
                  event) comprising eight percent (80%) or more of the voting
                  power for all purposes of the surviving or resulting
                  corporation; or (d) the stockholders of Neoprobe approve a
                  transfer of substantially all of the assets of Neoprobe to
                  another person other than a transfer to a transferee, eighty
                  percent (80%) or more of the voting power of which is owned or
                  controlled by Neoprobe or by the holders of Neoprobe's voting
                  securities issued and outstanding immediately before such
                  transfer in the same relative proportions to each other as
                  existed before such event. The parties hereto agree that for
                  the purpose of determining the time when a Change of Control
                  has occurred that if any transaction results from a definite
                  proposal that was made before the end of the Term of this
                  Employment Agreement but which continued until after the end
                  of the Term of this Employment Agreement and such transaction
                  is consummated after the end of the Term of this Employment
                  Agreement, such transaction shall be deemed to have occurred
                  when the definite proposal was made for the purposes of the
                  first sentence of this paragraph G of this Section 4.

         H.       BENEFIT AND STOCK PLANS. In the event that a benefit plan or
                  Stock Plan which covers the Employee has specific provisions
                  concerning termination of employment, or the death or
                  disability of an employee (e.g., life insurance or disability
                  insurance), then such benefit plan or Stock Plan shall control
                  the disposition of the benefits or stock options.

5.       PROPRIETARY INFORMATION AGREEMENT. Employee has executed a Proprietary
         Information Agreement as a condition of employment with the Company.
         The Proprietary Information Agreement shall not be limited by this
         Employment Agreement in any manner, and the Employee shall act in
         accordance with the provisions of the Proprietary Information Agreement
         at all times during the Term of this Employment Agreement.

6.       NON-COMPETITION. Employee agrees that for so long as he is employed by
         the Company under this Employment Agreement and for one (1) year
         thereafter, the Employee will not:

         A.       enter into the employ of or render any services to any person,
                  firm, or corporation, which is engaged, in any part, in a
                  Competitive Business (as defined below);

         B.       engage in any Competitive Business for his own account;

         C.       become associated with or interested in through retention or
                  by employment any Competitive Business as an individual,
                  partner, shareholder, creditor, director, officer, principal,
                  agent, employee, trustee, consultant, advisor, or in any other
                  relationship or capacity; or

         D.       solicit, interfere with, or endeavor to entice away from the
                  Company, any of its customers, strategic partners, or sources
                  of supply.

                  Nothing in this Employment Agreement shall preclude Employee
                  from taking employment in the banking or related financial
                  services industries nor from investing his personal assets in
                  the securities or any Competitive Business if such securities
                  are traded on a national stock exchange or in the
                  over-the-counter market and if such investment does not result
                  in his beneficially owning, at any time, more than one percent
                  (1%) of the publicly-traded equity securities of such
                  Competitive Business. "Competitive Business" for purposes of
                  this Employment Agreement shall mean any business or
                  enterprise which:

                  a.       is engaged in the development and/or
                           commercialization of products and/or systems for use
                           in (1) intraoperative detection of cancer and/or (2)
                           Activated Cellular Therapy for cancer, or
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                  b.       reasonably understood to be competitive in the
                           relevant market with products and/or systems
                           described in clause a above, or

                  c.       the Company engages in during the Term of this
                           Employment Agreement pursuant to a determination of
                           the Board of Directors and from which the Company
                           derives a material amount of revenue or in which the
                           Company has made a material capital investment.

         The covenant set forth in this Section 6 shall terminate immediately
         upon the substantial completion of the liquidation of assets of the
         Company or the termination of the employment of the Employee by the
         Company without cause or at the end of the Term of this Employment
         Agreement.

7.       GOVERNING LAW. The Employment Agreement shall be governed by and
         construed in accordance with the laws of the State of Ohio.

8.       VALIDITY. The invalidity or unenforceability of any provision or
         provisions of this Employment Agreement shall not affect the validity
         or enforceability of any other provision of the Employment Agreement,
         which shall remain in full force and effect.

9.       ENTIRE AGREEMENT. This Employment Agreement constitutes the entire
         understanding between the parties with respect to the subject matter
         hereof, superseding all negotiations, prior discussions, and
         preliminary agreements. This Employment Agreement may not be amended
         except in writing executed by the parties hereto.

10.      EFFECT ON SUCCESSORS OF INTEREST. This Employment Agreement shall inure
         to the benefit of and be binding upon heirs, administrators, executors,
         successors and assigns of each of the parties hereto. Notwithstanding
         the above, the Employee recognizes and agrees that his obligation under
         this Employment Agreement may not be assigned without the consent of
         the Company.

IN WITNESS WHEREOF, the parties hereto have executed and deliverd this
Employment Agreement as of the date first written above.


NEOPROBE CORPORATION                                EMPLOYEE

By: /s/ David C. Bupp                               /s/ Brent L. Larson
   ----------------------------                     ----------------------------
     David C. Bupp, President                       Brent L. Larson