NEOPROBE CORP
10QSB/A, 1997-05-13
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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<PAGE>   1
                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                  FORM 10-QSB/A


     (MARK ONE)

                       QUARTERLY REPORT UNDER SECTION 13 OR 15(d) OF THE
         /x/                    SECURITIES EXCHANGE ACT OF 1934
                      For the quarterly period ended: September 30, 1996

                                              OR

        / /           TRANSITION REPORT UNDER SECTION 13 OR 15(d) OF THE
                                         EXCHANGE ACT

                 For the transition period from ______ to______


   
                         COMMISSION FILE NUMBER: 0-26520
    


                              NEOPROBE CORPORATION
        (Exact name of small business issuer as specified in its charter)

     DELAWARE                                           31-1080091
(State or other jurisdiction of             (I.R.S. employer identification no.)
 incorporation or organization)


              425 METRO PLACE NORTH, SUITE 400, DUBLIN, OHIO 43017
                    (Address of principal executive offices)


                                  614-793-7500
                (Issuer's telephone number, including area code)


   
This Amendment No. 3 is being filed for the purpose of re-filing Exhibit
10.4.20. 
    
<PAGE>   2
                           PART II - OTHER INFORMATION

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K.

     (A)  LIST OF EXHIBITS AND FINANCIAL STATEMENTS INCORPORATED BY REFERENCE

           (3)      ARTICLES OF INCORPORATION AND BY-LAWS

           3.1.     Restated Certificate of Incorporation of Neoprobe
                    Corporation, as corrected February 18, 1994 and as amended
                    June 27, 1994, July 25, 1995 and June 3, 1996 (incorporated
                    by reference to Exhibit 99.2 to the Registrant's Current
                    Report on Form 8-K dated June 20, 1996; Commission File No.
                    0-20676).

           3.2.     Amended and Restated By-Laws dated July 21, 1993 (as amended
                    July 18, 1995 and May 30, 1996) (incorporated by reference
                    to Exhibit 99.4 to the Registrant's Current Report on Form
                    8-K dated June 20, 1996; Commission File No. 0-20676).

           (4)      INSTRUMENTS DEFINING THE RIGHTS OF HOLDERS, INCLUDING
                    INDENTURES

           4.1.     See Articles FOUR, FIVE, SIX and SEVEN of the Restated
                    Certificate of Incorporation of the Registrant (see Exhibit
                    3.1).

           4.2.     See Articles II and VI and Section 2 of Article III and
                    Section 4 of Article VII of the Amended and Restated By-Laws
                    of the Registrant (see Exhibit 3.2).

           4.3.     Specimen of Class E Redeemable Common Stock Purchase Warrant
                    certificate (incorporated by reference to Exhibit 4.9 to the
                    registration statement on Form S-1; No. 33-51446).

           4.4.     Warrant Agreement dated November 10, 1992 between Registrant
                    and Continental Stock Transfer & Trust Company (incorporated
                    by reference to Exhibit 4.4 to the Registrant's Annual
                    Report on Form 10-KSB for the fiscal year ended December 31,
                    1992; Commission File No. 0-20676).

           4.5.     Supplemental Warrant Agreement dated November 12, 1993
                    between the Registrant and Continental Stock Transfer &
                    Trust Company (incorporated by reference to Exhibit 4.5 of
                    registration statement on Form S-3, No. 33-72658).

           4.6.     Rights Agreement dated as of July 18, 1995 between the
                    Registrant and Continental Stock Transfer & Trust Company
                    (incorporated by reference to Exhibit 1 of the registration
                    statement on Form 8-A; Commission File No. 0-20676).

           (10)     MATERIAL CONTRACTS.

           10.1.1. - 10.1.26.       Reserved.

           10.2.1. - 10.2.33.       Reserved.

           10.3.1. - 10.3.46.       Reserved.

           10.4.1 - 10.4.19.        Reserved.


                                       3
<PAGE>   3
   
           10.4.20. License and Distribution Agreement dated September 18, 1996
                    between Registrant and United States Surgical Corporation
                    (filed pursuant to Rule 24b-2 under which the Registrant has
                    requested confidential treatment of certain portions of this
                    exhibit, which were omitted and which have been filed 
                    separately with the Commission).
    

           (11)     STATEMENT REGARDING COMPUTATION OF PER SHARE EARNINGS.

           11.1.    Computation of Net Loss Per Share.*

           (27)     FINANCIAL DATA SCHEDULE.

           27.1.    Financial Data Schedule (submitted electronically for SEC
                    information only).*


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

* Previously filed


                                       4
<PAGE>   4
                                   SIGNATURES


In accordance with the requirements of the Exchange Act, the Registrant caused
this report to be signed on its behalf by the undersigned, thereunto duly
authorized.

                                      NEOPROBE CORPORATION
                                               (Registrant)


                                      By:  s/David C. Bupp
                                          -----------------------------------
                                          David C. Bupp, President and Chief
                                          Operating Officer

   
Dated:  May 13, 1997
    


                                      By:  s/John Schroepfer
                                          -----------------------------------
                                          John Schroepfer, Vice President
                                          Finance & Administration
                                          (Principal Financial and Accounting
                                          Officer)


<PAGE>   5
                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
     EXHIBIT                                                                          PAGE IN MANUALLY
     NUMBER                             DESCRIPTION                                   SIGNED ORIGINAL


<S>                <C>                                                                      <C>
        3.1.       Restated Certificate of Incorporation of Neoprobe
                   Corporation, as corrected February 18, 1994 and as amended                *   
                   June 27, 1994, July 25, 1995 and June 3, 1996

        3.2.       Amended and Restated By-Laws dated July 21, 1993 (as                      *
                   amended July 18, 1995 and May 30, 1996)

        4.1.       See Articles FOUR, FIVE, SIX and SEVEN of the
                   Restated Certificate of Incorporation of Registrant
        4.2.
                   See Articles II and VI and Section 2 of Article III and
                   Section 4 of Article VII of the Amended and Restated By-Laws
                   of Registrant
        4.3.
                   Specimen of Class E Redeemable Common Stock Purchase
                   Warrant                                                                   *

        4.4.       Warrant Agreement dated November 10, 1992                                 *

        4.5.       Supplemental Warrant Agreement dated November 12, 1993                    *   
                                                                                             

        4.6.       Rights Agreement between the Registrant and
                   Continental Stock Transfer & Trust Company dated July
                   18, 1995                                                                  *

10.1.1.-10.1.26    Reserved

10.2.1.-10.2.33.   Reserved

10.3.1.-10.3.46.   Reserved

10.4.1.-10.4.17.   Reserved

   
    10.4.20.       License and Distribution Agreement dated September 18, 1996
                   between Registrant and United States Surgical Corporation
                   (filed pursuant to Rule 24b - 2 under which the Registrant
                   has requested confidential treatment of certain portions of
                   this exhibit, which were omitted and which have been filed 
                   separately with the Commission).
    

       11.1.
                   Computation of Net Loss Per Share                                         *

       27.1.       Financial Data Schedule (submitted electronically for                     *
                   SEC information only).
</TABLE>

* Previously filed.


                                       6



<PAGE>   1
                                                                 Exhibit 10.4.20


                      LICENSE AND DISTRIBUTORSHIP AGREEMENT

         This Agreement (the "Agreement"), dated and effective as of September
18, 1996 by and between Neoprobe Corporation ("Neoprobe"), a corporation duly
organized and existing under the laws of the State of Delaware and having its
principal place of business at 425 Metro Place North, Suite 400, Dublin Ohio
43017-1367, and United States Surgical Corporation ("USSC"), a corporation duly
organized and existing under the laws of the State of Delaware and having its
principal place of business at 150 Glover Avenue, Norwalk, Connecticut 06856
("Neoprobe and USSC, each a "Party" and collectively, the "Parties").

         WHEREAS, Neoprobe has developed and is developing proprietary
radioreceptor and radioimmunoguided surgery technologies for the detection of
cancer;

         WHEREAS, USSC develops, manufactures and markets surgical devices and
products; and

         WHEREAS, Neoprobe desires to grant certain marketing rights to USSC for
such surgery technologies and USSC wishes to acquire such marketing rights from
Neoprobe all on the terms set forth in this Agreement;

         NOW, THEREFORE, in consideration of the mutual promises, covenants and
agreements hereinafter set forth, the parties hereto agree as follows:

                             ARTICLE 1 - DEFINITIONS

         1.1 For purposes of this Agreement, the definitions set forth below
shall be applicable.


                                        1


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   2
         "Act" shall mean the United States Food, Drug and Cosmetic Act of 1938,
as amended to date and during the term of this Agreement, including, without
limitation the Medical Device Amendments of 1976.

         "Action" shall mean a claim, action, suit, proceeding or arbitration.

         "Affiliate" shall mean with respect to any specified Person, any other
Person that directly or indirectly through one or more intermediaries, controls,
or is controlled by, or is under common control with, the Person specified. For
purposes of this definition, "control" including, with correlative meanings, the
terms "controlled by" and "under common control with" means ownership directly
or indirectly of more than fifty percent (50%) of the equity capital having the
right to vote for election of directors in the case of a corporation and more
than fifty percent (50%) of the beneficial interest in the business entity other
than a corporation.

         "Confidential Information" shall mean, unless specified in writing to
the contrary, any proprietary information or material regarding the business or
affairs of USSC or Neoprobe including, without limitation, Know-How (defined
below), research, development, customer lists and marketing information;
provided, however, that "Confidential Information" shall not include information
that (i) can be demonstrated to have been in the public domain or publicly known
prior to the date of disclosure by the disclosing Party; or (ii) that can be
demonstrated from written records, to have been in the receiving Party's
possession from another source not under an obligation of secrecy to the
disclosing Party prior to disclosure by the disclosing Party; or (iii) that
becomes part of the public domain or publicly known by publication or otherwise,
not due to any unauthorized act by the receiving Party; or (iv) that can be
demonstrated by written records to have been independently developed by the
receiving Party without the use of the disclosing Party's Confidential
Information.


                                       2


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   3
         "Control Unit" shall mean an intraoperative radiation detection device
including, without limitation, a microcomputer-based unit which measures the
presence of gamma-emitting isotopes; the unit translates the gamma pulsers
received from the Probe (defined below) into understandable displays and sounds.

         "Costs" shall mean a party's manufacturing costs including material and
labor but excluding overhead, all as calculated in accordance with GAAP.

         "Excluded Countries" shall mean South Korea, North Korea, Singapore,
Malaysia, Taiwan and Thailand.

         "Extraordinary Transaction" shall mean the sale or other disposition
(whether by merger, consolidation, tender or exchange offer or otherwise) of all
or substantially all of the securities, assets or business of Neoprobe in a
single transaction or a series of transactions.

         "FDA" shall mean the United States Department of Health and Human
Services, Food and Drug Administration, or any successor governmental
organization.

         "GAAP" shall mean generally accepted accounting principles.

         "Regulatory Approvals" shall mean approval to market a Neoprobe Product
by the FDA under the Act and by International Regulatory Agencies (defined
below).

         "Field" shall mean all surgical applications relating to one or more
types of cancers including, without limitation, the use of Neoprobe Products and
Neoprobe Product Improvements in the detection, diagnosis, prevention, staging
and treatment of cancers (e.g. colorectal, ovarian and prostate cancers). The
Field shall also include, without limitation, the use of Neoprobe Products and
Neoprobe Product Improvements relating to surgical detection, diagnosis,


                                       3


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   4
prevention, staging and treatment of cancers by means of sentinel node mapping
(intraoperative lymphoscintigraphy) and adoptive cellular therapy.

         "Improvement" shall mean any adaption, improvement, redesign or
modification.

         "International Regulatory Agency" shall mean any national, provincial,
state or local governmental agency or other organization outside of the United
States which performs functions similar to the FDA.

         "Laws" shall mean any statute, regulation, rule, ordinance, guideline,
order, judgment, decision or interpretation of the FDA or any International
Regulatory Agency.

         "Neoprobe Product" or "Neoprobe Products" shall include intraoperative
radiation detection devices, localization or targeting agents and disposable
devices, and all parts, components or subassemblies thereof or accessories
therefor, and all Neoprobe Product Improvements (defined below), unless
otherwise expressly stated herein. Neoprobe Products shall include, but shall
not be limited to, the following: RIGScan (defined below), the Control Unit
(defined below) and the Probe (defined below) but shall also include other
Neoprobe Products, and Technology and Improvements related thereto.

         "Neoprobe Product Improvements" shall mean any Improvement of a
Neoprobe Product.

         "Net Sales" with respect to USSC Royalty Products shall mean gross
sales of USSC Royalty Products billed and shipped by USSC or its Affiliates,
Sublicensees or permitted assignees less allowances and discounts actually
allowed (other than advertising allowances, or fees or commissions to salesmen
or sales representatives), returns, invoices written off as uncollectable,
billed taxes and customs duties, costs of transportation, freight and transit
insurance, and shall not include samples or demonstration materials or any sales
to USSC


                                       4


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   5
employees for any reason other than resale. The term "Net Sales" shall
not include sales between USSC and its Affiliates, Sublicensees or permitted
assignees. For purposes of the "Net Sales" definition, the term USSC Royalty
Products shall also include USSC Royalty Products sold in packages, trays or
other groups of items consisting of one or more USSC Royalty Products and one or
more non-USSC Royalty Products (the "Package"). ****

         "Net Sales" with respect to Neoprobe Products shall mean the actual
invoice price at which Neoprobe Product is sold by Neoprobe or its Affiliates or
permitted assignees in the Territory less the following: trade, cash and
quantity discounts; returns; invoices written off as uncollectable, normal trade
allowances, charge backs, rebates and adjustments; and billed taxes and customs
duties, costs of transportation, freight and transit insurance. ****

         "Patents" or "Patent Rights" shall mean any and all world-wide patents
and patent applications relating to the Neoprobe Products presently or hereafter
owned by Neoprobe or a Neoprobe Affiliate and/or in which Neoprobe or a Neoprobe
Affiliate has or obtains any right, title or interest including, without
limitation the patent, patent applications set forth on Exhibit A-1 attached
hereto.


                                       5


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   6
         "Person" or "Persons" shall mean any individual, corporation,
partnership, association, trust or other entity or organization including a
governmental or political sub division or any agency or instrumentality thereof.

         "Probe" shall mean a radiation sensing probe including, without
limitation, a gamma radiation sensing probe and a laparoscopic radiation sensing
probe.

         "Regulatory Authorities " shall mean collectively, the FDA and the
International Regulatory Agencies.

         "Rights Technology" shall mean any and all secret or confidential
information, trade secrets, specifications, tests results, analyses, data,
inventions, modifications and improvements, methods, processes, formulae,
compositions, designs, techniques, applications, ideas or concepts, whether or
not reduced to practice, including, without limitation, technology that is or
could be the subject matter of a foreign or domestic patent or patent
application, whether or not reduced to writing in a patent application as to
which (i) Neoprobe either conceives or develops during the term of this
Agreement, or (ii) Neoprobe has, or during the term of this Agreement obtains,
any rights, title or interest, in either case, that has an intraoperative
surgical application relating to cancer or any other disease, pathology or
condition and is not otherwise subject to USSC's rights under this Agreement.

         "RIGScan" shall mean a radiolabelled monoclonal antibody, fragment or
peptide including, without limitation, a CC49 monoclonal antibody radiolabelled
with Iodine 125.

         "RIGScan System" shall mean Neoprobe Products consisting of a RIGScan,
a Control Unit and a Probe.

         "Sublicensee" shall mean any third Person to whom USSC grants a
sublicense to sell the Product.


                                       6


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   7
         "Technology" shall mean any and all secret or confidential information,
trade secrets, specifications, tests results, analyses, data, inventions,
modifications and improvements, methods, processes, formulae, compositions,
designs, techniques, applications, ideas or concepts, whether or not reduced to
practice, including, without limitation, technology that is or could be the
subject matter of a foreign or domestic patent or patent application, whether or
not reduced to writing in a patent application involving or relating to
radioreceptor and/or radioimmunoguided surgery techniques.

         "Territory" shall mean every country, possession and territory
throughout the world, except the Excluded Countries.

         "Trademarks" or "Trademark Rights" shall mean any and all world-wide
trademarks and trademark applications and copyrights relating to the Neoprobe
Products presently or hereafter owned by Neoprobe or a Neoprobe Affiliate and/or
in which Neoprobe or a Neoprobe Affiliate has or obtains any right, title or
interest including, without limitation, the trademark and trademark applications
set forth on Exhibit A-2 attached hereto.

         "USSC Royalty Products" shall mean surgical products and devices for
use with Neoprobe Products in the Field ****. Without limiting the foregoing,
USSC Royalty Products shall include disposable products for use either with a
Probe or with a radiation sensing element of a Probe. USSC Royalty Products
shall not include (i) any USSC product except if designed and sold primarily for
use with a Neoprobe Product, and (ii) shall in no event include trocars,
staplers, staples, clip appliers, clips, sutures, ABBI* products or any other
device or product which is marketed primarily for other uses.


                                       7


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   8
         "Warranty" shall mean the warranty on the Neoprobe Products which shall
be established after the date of this Agreement and shall be set forth in
Exhibit C attached hereto.

         1.2 In addition to the foregoing defined terms, the following terms
shall have the meanings set forth in the referenced Sections of this Agreement:

<TABLE>
<CAPTION>
                  Term                                                       Section
                  ----                                                       -------
<S>                                                                            <C>
                  ****                                                         14.2
                  Demonstration Source                                          3.5
                  Development Committee                                         5.1
                  ****                                                         14.2
                  ****                                                         14.2
                  Dow                                                          14.2
                  First Exclusive Negotiation Period                           11.2
                  Force Majeure Event                                          15.1
                  ****                                                          2.2
                  ****                                                          2.2
                  Licensors                                                    14.2
                  Licenses                                                     14.2
                  Marketing Rights                                              3.1
                  Material IPRs                                                14.2
                  Minimum Selling Price                                         3.6
                  NCI Agreement                                                14.2
                  Neoprobe Indemnitees                                          9.1
                  Neoprobe Inventions                                           8.1
                  Neoprobe Regulatory Lead Situation                            7.2
                  Promotional Materials                                         3.2
                  R&D Payments                                                  4.1
                  Renewal Option                                               12.2
                  Royalty                                                       4.1
                  Sales Penetration Level                                      10.3
                  Second Exclusive Negotiation Period                          11.3
</TABLE>


                                       8


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   9
<TABLE>
<S>                                                                            <C>
                  Term                                                         12.1
                  Trademark License                                             2.1
                  USSC Commission                                               4.3
                  USSC Indemnitees                                              9.1
                  USSC Inventions                                               8.1
</TABLE>


                   ARTICLE 2 - APPOINTMENT; EXCLUDED COUNTRIES

         2.1

         (a) For the term of this Agreement, Neoprobe hereby appoints USSC as
its sole and exclusive marketer throughout the Territory for Neoprobe Products
in the Field, alone or together with USSC Royalty Products. In connection with
such appointment, Neoprobe hereby grants to USSC the following:

         (i) Marketing Rights (defined below) during the term of this Agreement;

and

         (ii) a non-exclusive **** license, with right to sublicense, under the
Patents in the Territory to market Neoprobe Products in the Field, such license
to continue during the term of this Agreement, or, in the case of a particular
patent within Patents, for the duration of such patent; and

         (iii) a license under the Trademarks in the Territory as set forth in
Exhibit 2.1 (the "Trademark License"), such license to continue during the term
of this Agreement. The form of Trademark License set forth in Exhibit 2.1 shall
be executed by both parties simultaneously with the execution of this Agreement.

         (b) All references in the Agreement to rights and obligations of USSC
with respect to the Neoprobe Products and USSC Royalty Products shall also be
deemed to include Affiliates, Sublicensees and permitted assigns of USSC.


                                       9


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   10
         2.2

         ****

         2.3 ****


                         ARTICLE 3 - MARKETING AND SALES

         3.1 Subject to Section 3.2, USSC's Marketing Rights in the Territory
for Neoprobe Products in the Field shall include the following: (a) exclusive
right to market and solicit orders including, without limitation, advertise,
promote sales and contact potential customers, prepare and distribute marketing
and sales brochures and materials, pursue sales leads, answer customer
inquiries, make quotations and take orders, and (b) exclusively train customers
of Neoprobe Products with such assistance by Neoprobe as provided in this
Article 3. All communications or inquiries received by Neoprobe from potential
customers for Neoprobe Products and/or USSC Royalty Products shall be promptly
forwarded by Neoprobe to USSC. All decisions regarding USSC marketing,
solicitation, answering customer inquiries and training shall be in USSC's sole
discretion.

         3.2 Neoprobe is legally responsible for all Neoprobe Product
advertising, promotional material, sales aids, sales brochures and product
labeling and packaging under the Act (collectively, "Promotional Materials").
Accordingly, approval of any particular Promotional Material for use in
marketing a Neoprobe Product for regulatory compliance purposes shall be the
sole


                                       10


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   11
responsibility of Neoprobe. USSC shall submit all Promotional Materials
prepared for use with marketing a Neoprobe Product for prior review and approval
by Neoprobe, which approval shall not be unreasonably delayed or denied. If any
Promotional Materials have been previously approved by Neoprobe, USSC shall not
be required to resubmit such Promotional Materials for Neoprobe's review and
approval.

         3.3 USSC shall promote a Neoprobe Product only for indications covered
by the labeling or literature which accompany the Neoprobe Product and which
have been approved, cleared or otherwise allowed by the applicable Regulatory
Authorities in the country in which such promotion occurs.

         3.4

         (a) Neoprobe shall provide training with respect to Neoprobe Products
to USSC's marketing and sales personnel and, in accordance with USSC's requests,
to customers procured by USSC. Such training shall be conducted by competent,
technically qualified employees or representatives of Neoprobe. Neoprobe shall
bear the expense associated with such training as they relate to Neoprobe's
employees or representatives; USSC shall bear the expenses associated with such
training as they relate to the training facility and supplies, other than
Neoprobe Products. Neoprobe training of USSC's marketing and sales personnel
shall occur at such times and locations as are mutually agreed consistent with
the mutually beneficial objective of the parties to effect rapid and thorough
training of USSC's marketing and sales personnel to maximize sales of Neoprobe
Products and USSC Royalty Products.

         (b) USSC shall permit Neoprobe employees to attend and observe USSC's
product launch salesforce meetings for a Neoprobe Product and surgeon training
programs for a Neoprobe Product, but only for those portions of such meetings
and programs during which USSC's employees or its representatives present or
demonstrate the Neoprobe Product.


                                       11


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   12
         3.5 Neoprobe shall make available to USSC **** Control Units, ****
Probes and **** demonstration sources (such **** demonstration sources to be
replenished when such demonstration sources cease to meet Neoprobe's radiation
activity specifications) which mimic RIGScan for use in demonstrating RIGScan
("Demonstration Source"). Any additional Control Units, Probes or Demonstration
Source required by USSC shall be purchased from Neoprobe ****. Neoprobe shall
make available to USSC demonstration product for other Neoprobe Products on
similar terms. All demonstration product purchased by USSC pursuant to this
Section 3.5 ("Demonstration Product") shall be used only for demonstration
purposes and not for subsequent resale by USSC. ****

         3.6

         (a) Non price terms and conditions of Neoprobe sales to customers and
the Warranty have not yet been established. Neoprobe shall establish non price
terms and conditions (including, without limitation, a return goods policy and a
loaner policy for reusable Neoprobe Products), a Warranty and out of warranty
repair and service program on terms reasonably acceptable to USSC prior to
launch of the Neoprobe Product. When established, the non price terms and
conditions and Warranty shall be set forth in Exhibit 3.6 and Exhibit B,
respectively.

         (b) Neoprobe shall accept and fill Neoprobe Product purchase orders
forwarded to it by USSC, Customer purchaser orders for Neoprobe Products
obtained by USSC shall be deemed accepted by Neoprobe upon receipt by Neoprobe.
****


                                       12


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   13
Customer purchase orders for Neoprobe Products obtained by USSC shall be 
solely for Neoprobe's account and risk and shall be promptly forward by USSC
to Neoprobe.

         3.7 The Parties shall continuously communicate and update each other
concerning customer purchase orders, customer pricing and purchase terms,
shipping and delivery of Neoprobe Products, and customer invoicing, payment and
complaints. Notwithstanding the foregoing, Neoprobe Products shall be invoiced,
shipped and delivered to customers directly by Neoprobe or its representatives
employing such shipping and delivery arrangements as Neoprobe, in its
discretion, shall determine. Neoprobe shall also have sole responsibility for
customer payments and collections and shall be solely responsible for warranty
repairs, loaners and service and out-of-warranty repairs, loaners and service
for Neoprobe Products. USSC shall have no right, responsibility or liability for
order processing, invoicing, shipping or delivery of Neoprobe Products, billing
or collection with respect thereto or the repair or service thereof, whether
under warranty or otherwise.

         3.8 Notwithstanding anything in this Agreement to the contrary, USSC
shall have the exclusive right and license, with right to sublicense, to
develop, manufacture, sell and deliver USSC Royalty Products to Neoprobe
customers in the Territory. Neoprobe shall have no right, responsibility or
liability for order processing, invoicing, shipping or delivery of USSC Royalty
Products, billing or collection with respect thereto or the repair or service
thereof, whether under warranty or otherwise.


                                       13


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   14
                            ARTICLE 4 - CONSIDERATION

         4.1 The total consideration to be paid to Neoprobe by USSC for the
exclusive marketing rights granted hereunder, the Trademark License, the
non-compete undertaking set forth in Section 10.2 herein, and the other rights
in this Agreement shall consist of the following:

                  (a) Upfront License Fee: A payment of Two Million Dollars
($2,000,000) payable to Neoprobe within two (2) business days of execution of
this Agreement, which payment shall be non-refundable on the condition that the
term of this Agreement is not terminated by USSC pursuant to Section 12.3(a)-(f)
herein within twenty four (24) months after the Effective Date in which case
Neoprobe shall promptly refund to USSC the total amount of the aforesaid Upfront
License Fee.

                  (b)  Additional License Fees:

                           (i) U.S. Approval: Two Million Dollars ($2,000,000)
payable to Neoprobe upon issuance to Neoprobe of all required regulatory
approvals by the FDA for the commercial marketing of a RIGScan System with
RIGScan CC49.

                           (ii) European Approval: One Million Five Hundred
Thousand Dollars ($1,500,000) payable to Neoprobe upon issuance to Neoprobe of
all required regulatory approvals by the European governmental authorities that
are the counterparts to the FDA for the commercial marketing of a RIGScan System
with RIGScan CC49.

                  (c) Research and Development Payments: Payments ("R&D
Payments") equal to (i) ****


                                       14


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   15
                  (d) Royalty on USSC Royalty Products: a periodic royalty
("Royalty") equal to **** . Payment of such amounts to Neoprobe shall be made 
as provided in Section 4.2 below.

         4.2 For purposes of Section 4.1(d) above, Net Sales shall not include
sales of USSC Royalty Products between the parties hereto, sales of USSC Royalty
Products by independent distributors, sales of USSC Royalty Products between or
among USSC and its Affiliates or permitted assignees, demonstration USSC Royalty
Products, or returns of USSC Royalty Products. USSC shall deliver quarterly
written reports to Neoprobe for each three (3) month period ending on the last
days of the months of March, June, September and December of each year, within
forty-five (45) days after the end of each such period. The report shall set
forth the number of USSC Royalty Products sold by USSC, its Affiliates and
permitted assignees during the immediately preceding calendar quarter and the
amount of the Royalty payable to Neoprobe. All information contained in such
quarterly reports shall be treated as USSC's Confidential Information.
Simultaneously with the submission of each report, USSC shall pay to Neoprobe by
check or bank transfer the amount of Royalties due to Neoprobe for the report
period under the terms of this Agreement. USSC shall maintain records in
sufficient detail and, upon reasonable notice, allow any independent certified
public accounting firm of nationally recognized standing, appointed by Neoprobe
and reasonably acceptable to USSC to examine its consolidated books and records.
Such examinations shall occur on or after February 15 of any calendar year (or,
if Neoprobe appoints for purposes of such examination the accounting firm
employed by USSC to conduct its regular annual audit, prior to February 15,)
only during normal business hours and not more than once a year, and shall be
solely for the purpose of verifying the calculation of Royalties due under this
Agreement. A final such examination may occur once during the year immediately
succeeding termination of this Agreement. In the event Neoprobe appoints for the
purpose of examining USSC's consolidated books and records the accounting firm
employed by USSC to conduct its regular annual audit, and if the examination
provided for herein is performed at substantially


                                       15


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   16
the same time as such regular annual audit, the fees and expenses of the
accounting firm performing the examination shall be borne by USSC. In any other
event, the fees and expenses of the accounting firm performing the examination
shall be borne by Neoprobe. Unless written objection is made by Neoprobe and
delivered to USSC within thirty (30) days after completion of such examinations,
the calculation of Royalties paid by USSC prior to the date of such examination
shall be final and binding on the Parties, except insofar as adjusted or
corrected as a result of USSC's regular annual audit. It is understood that USSC
shall not be required to furnish or permit the examination of the identities, at
any time, of customers or other information as to specific sales. Any
information provided to Neoprobe or its accountants pursuant hereto shall be
treated as USSC's Confidential Information.

         4.3 In consideration for USSC marketing the Neoprobe Products pursuant
to this Agreement and for the non-compete undertaking set forth in Section 10.2
herein, Neoprobe agrees to pay to USSC a commission on Net Sales of Neoprobe
Products (collectively, "USSC Commissions") including the following:

                  (a) USSC Commissions on Net Sales of the RIGScan System
(including without limitation, a RIGScan System which includes a CC49 monoclonal
antibody radiolabelled with Iodine 125) as calculated in accordance with Exhibit
4.3, attached hereto; and

                  (b) USSC Commissions on other Neoprobe Products equivalent in
amount to USSC Commissions on the RIGScan System set forth in Section 4.3(a)
above. The Parties shall negotiate with each other in good faith concerning such
equivalent commission prior to the commencement of sale of each other Neoprobe
Products and Technologies.

         4.4


                                       16


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   17
         (a) For purposes of Section 4.3 above, Net Sales shall not include
sales of Neoprobe Products between the parties hereto, demonstration Neoprobe
Products, or returns of Neoprobe Products. Net Sales shall also include lease
payments, per treatment charges or similar consideration, if any, due to
Neoprobe with respect to Neoprobe Products transferred to third persons. Without
limiting the foregoing, consideration received by Neoprobe in connection with
leasing arrangements with third parties shall be considered as sales for purpose
of calculating Net Sales.

         (b) Neoprobe shall deliver fax or written reports to USSC with respect
to customer orders for Neoprobe Products on a daily basis. The report shall set
forth the number of Neoprobe Products sold by Neoprobe, its Affiliates and
permitted assignees to each customer, the address thereof and customer contact
person. All information contained in such reports shall be treated as Neoprobe's
Confidential Information except that USSC may utilize such information for sales
of USSC Royalty Products and for other purposes contemplated by this Agreement.

         (c) Within fifteen (15) days following each calendar month during the
term of this Agreement, Neoprobe shall pay to USSC by check or bank transfer
**** . Neoprobe shall maintain records in sufficient detail and, upon
prior notice, shall allow any independent certified public accounting firm of
nationally recognized standing, appointed by USSC and reasonably acceptable to
Neoprobe, to examine Neoprobe's consolidated books and records for purposes of
determining the amount of USSC Commissions.


                      ARTICLE 5 - RESEARCH AND DEVELOPMENT


                                       17


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   18
          5.1 The Parties agree that one of the aims of their relationship is
the further commercialization of Neoprobe Products and the development of
Improvements to Neoprobe Products which are compatible and complementary with
USSC Royalty Products and function in a manner designed to protect, to the
maximum extent reasonably possible, the intellectual property rights of the
parties and the distinctiveness of the Neoprobe Products with USSC Royalty
Products in the marketplace, and shall design or redesign their respective
products for use in the Field consistent with the foregoing objectives. Without
limiting the foregoing, (i) Neoprobe shall not alter the design the Control Unit
so that it will not function with a USSC Royalty Product, and (ii) USSC shall
not alter the design of a USSC Royalty Product designed for use with a Neoprobe
Product so that such USSC Royalty Product will not function with such Neoprobe
Product. The monies paid to Neoprobe pursuant to Section 4.1(c) shall be used by
Neoprobe solely to fund research and development of Neoprobe Products and
Improvements to Neoprobe Products directed to those areas in which USSC has or
retains rights under this Agreement and for no other purpose, without USSC's
approval in its sole and absolute discretion. **** Neoprobe shall maintain
records in sufficient detail and, upon prior notice, shall allow USSC or any
independent certified public accounting firm of nationally recognized standing,
appointed by USSC, to examine Neoprobe's records to assure Neoprobe's compliance
with this Section 5.1

         5.2 ****


                                       18


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   19
         5.2 R&D Payments shall be used by Neoprobe exclusively to fund further
development of Neoprobe Products including, without limitation, clinical trials
directed to those applications in which USSC has or retains rights under this
Agreement and expressed USSC's interest therein ****. Neoprobe shall maintain 
records in sufficient detail and, upon prior notice, shall allow any 
independent certified public accounting firm of nationally recognized standing, 
appointed by USSC and reasonably acceptable to Neoprobe, to examine Neoprobe's 
consolidated books and records to assure Neoprobe compliance with this Section 
5.2.

         5.3 Development of Neoprobe Products during the term of this Agreement
including, without limitation, the conduct of all clinical trails shall be the
exclusive responsibility of Neoprobe and at its sole cost. Neoprobe shall


                                       19


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   20
communicate with USSC and provide to USSC a copy of all test data and other
results concerning the further development of Neoprobe Products.


                       ARTICLE 6 - MANUFACTURE AND SUPPLY

         6.1 Neoprobe shall have sole right and shall have sole responsibility
and liability for the manufacture, assembly, production, quality control,
sterilizing, packaging, and labeling of the Neoprobe Products as well as the
shipping and delivery of the Neoprobe Products to customers.

         6.2 Neoprobe shall comply, and shall cause each of its third party
vendors, suppliers, distributors or other Persons involved in the manufacture,
assembly, production, packaging, labeling, shipping or delivery of Neoprobe
Products to comply, with all present and future Laws relating to the
manufacture, assembly, production, packaging, labeling, shipping delivery of the
Neoprobe Products, including, without limitation, those enforced or promulgated
by Regulatory Authorities (e.g. FDA good manufacturing practices, defect
notifications and any other registration requirements which may be imposed on
the manufacture, assembly or supply of drugs or medical devices).

         6.3 Neoprobe shall permit, or cause USSC to be permitted, to inspect
the manufacture, assembly, production, packaging, labeling, shipping, quality
control and sterilizing facilities of Neoprobe and its third party vendors,
suppliers and distributors, as well as all records relating to Neoprobe Products
to allow USSC to verify Neoprobe's compliance with its obligations under this
Agreement. Neoprobe shall notify USSC thirty (30) days prior to making, or any
third party making, any change in the design of a Neoprobe Product, in the
materials used to manufacture a Neoprobe Product or in the manufacturing process
thereof.

         6.4 Commencing with Regulatory Approval to sell a Neoprobe product, and
thereafter during the Term, Neoprobe shall maintain at its expense business


                                       20


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   21

interruption insurance with insurance carriers reasonably acceptable to USSC and
under which USSC is the sole covered party, such coverage to include claims for
liability, damage or loss to USSC, its Affiliates or permitted assignees caused
by Neoprobe being unwilling or unable to supply Neoprobe Products pursuant to
purchase orders procured by USSC or its Affiliates or permitted assignees, for
any or no reason, even if due to Force Majeure Event. The amount of such
coverage shall be based upon the reasonable estimate of the parties as to
expected sales of Neoprobe Product during the **** following such Regulatory
Approval and their business judgment exercised in a reasonable and prudent
manner, ****. Thereafter, the dollar amount of such coverage shall be adjusted
on the annual anniversary date of such Regulatory Approval during the Term to
reflect the reasonable estimate of the parties as to the expected sales of
Neoprobe Products during the **** and their business judgment exercised in a
reasonable and prudent manner, ****. Commencing with such Regulatory Approval,
Neoprobe shall furnish to USSC a certificate of insurance evidencing such
coverage with thirty days' written notice to USSC of cancellation or material
change. Thereafter, Neoprobe shall furnish to USSC on an annual basis an amended
or substitute certificate of insurance evidencing the adjustment to the dollar
amount of such coverage as provided hereinabove in this Section 6.4 and which
shall likewise contain a provision for thirty days' written notice to USSC of
cancellation or material change. Nothing set forth in this Section 6.4 is
intended to substitute for the indemnity rights set forth in this Agreement.


                             ARTICLE 7 - REGULATORY

         7.1

         (a) Neoprobe shall permit USSC to inspect and copy at USSC expense
Neoprobe's Regulatory Approvals at Neoprobe's principal offices on prior notice


                                       21


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   22
during regular business hours. Such Regulatory Approvals shall be retained by
USSC in confidence as Neoprobe's Confidential Information. Promptly following
the execution of this Agreement, Neoprobe shall provide to USSC a schedule to
the best of Neoprobe's knowledge containing a description of the timing,
clinical endpoints, indications approvals, and clinical protocols for all Phase
I, II and III clinical trials conducted, sponsored or funded, in whole or in
part, by Neoprobe or any Neoprobe Affiliate, or currently expected or
anticipated to be conducted, sponsored or funded, in whole or in part, by
Neoprobe or any Neoprobe Affiliate.

         (b) During the term of the Agreement, interaction with the FDA, any
International Regulatory Agency and any other similar authority within or
outside the United States concerning Neoprobe Products shall be conducted
exclusively by Neoprobe. For purposes of any regulatory filings concerning the
Neoprobe Products, Neoprobe shall be the official company sponsor. Neoprobe
shall advise USSC of regulatory communications with Regulatory Agencies
concerning Neoprobe Products and provide USSC with a copy of all proposed
filings with Regulatory Agencies concerning Neoprobe Products as far in advance
as is reasonably possible to permit USSC to comment upon the proposed filings.
In the event of a dispute between Neoprobe and USSC concerning any matter
relating to regulatory interaction with respect to Neoprobe Products, Neoprobe
shall have final authority to act, as Neoprobe deems appropriate with respect to
the matter in dispute. Neoprobe will assume and be solely responsible for all
costs associated with regulatory interaction concerning Neoprobe Products and
shall reimburse USSC its out-of-pocket costs, other than attorneys' fees and
expenses, associated with cooperation requested by Neoprobe in connection with
such regulatory interaction.

         7.2 During the term of the Agreement, interaction with the FDA, any
International Regulatory Agency and any other similar authority within or
outside the United States concerning USSC Royalty Products shall be conducted
exclusively by USSC, except to the extent and for so long as required to comply
with applicable regulatory requirements in a particular country in the Territory


                                       22


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   23
("Neoprobe Regulatory Lead Situation"). For purposes of any regulatory filings
concerning the USSC Royalty Products, USSC shall be the official company
sponsor, except for a Neoprobe Regulatory Lead Situation. Other than in respect
of a Neoprobe Regulatory Lead Situation, USSC shall advise Neoprobe of
regulatory communications with Regulatory Agencies concerning USSC Royalty
Products and provide Neoprobe with a copy of all proposed filings with
Regulatory Agencies concerning USSC Royalty Products as far in advance as is
reasonably possible to permit Neoprobe to comment upon the proposed filings. In
a Neoprobe Regulatory Lead Situation, Neoprobe shall advise USSC of regulatory
communications with Regulatory Agencies concerning USSC Royalty Provides and
shall submit to the appropriate Regulatory Agency USSC's proposed filing with
respect to the USSC Royalty Product or the portion of the Neoprobe filing
concerning the USSC's Royalty Product which shall be prepared by USSC, as the
case may be. In the event of a dispute between Neoprobe and USSC concerning any
matter relating to regulatory interaction with respect to USSC Royalty Products,
USSC shall have final authority to act, as USSC deems appropriate with respect
to the matter in dispute including, without limitation, in a Neoprobe Regulatory
Situation. USSC will assume and be solely responsible for all costs associated
with regulatory interaction concerning USSC Royalty Products and shall reimburse
Neoprobe its out-of-pocket costs, other than attorneys' fees and expenses,
associated with cooperation requested by USSC in connection with such regulatory
interaction including, without limitation, in a Neoprobe Regulatory Lead
Situation.

         7.3 Notwithstanding Sections 7.1 and 7.2 above, during the term of the
Agreement, the Parties shall use reasonable commercial efforts to coordinate
their regulatory filings concerning Neoprobe Products and USSC Royalty Products
and to facilitate concurrent regulatory approvals for Neoprobe Products and USSC
Royalty Products, and USSC shall have the right, in its discretion, to file and
prosecute, or cause Neoprobe to file and prosecute, applications for expedited
marketing approvals from Regulatory Agencies (e.g. amendments to existing PLAs
or 510(k) applications) with respect to probes and disposables (e.g.
laparoscopic probes and disposables).


                                       23


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   24
         7.4 Each Party shall notify the other Party as soon as practicable
after receiving notice of any Action involving or relating to Neoprobe Products
or USSC Royalty Products, as the case may be, which includes allegations of
violation of any applicable Laws. In addition, Each Party shall promptly notify
the other Party of any adverse reaction or other similar claims with respect to
a Neoprobe Product or a USSC Royalty Product of which it becomes aware. Any
death, serious injury, potential for occurrence of the same, or change in the
frequency or occurrence in field experiences required to be reported to the FDA
shall be reported by a Party to the other Party in a manner and time which will
enable the Party receiving the information to comply with applicable Laws in a
timely manner.

         7.5 Neoprobe shall by solely responsible to institute and fund any
recall, field corrective action, or the like in circumstances relating to a
Neoprobe Product defect or failure which requires such action as determined by
the FDA, any International Regulatory Agency or any other similar authority
within or outside the United States, or by Neoprobe or as otherwise may be
required pursuant to applicable Laws, except to the extent such action is the
result of a failure by USSC to limit its promotion of the Neoprobe Products to
indications approved, cleared or otherwise allowed by applicable Regulatory
Agencies. In such circumstances, the actual retrieval of the Neoprobe Products
will be the responsibility of Neoprobe and handled by Neoprobe or third Persons
authorized by Neoprobe. USSC shall assist Neoprobe in any such recall, field
corrective action, or the like and, subject to the exception set forth in the
first sentence of this Section 7.5, shall be reimbursed by Neoprobe for USSC's
out of pocket costs, other than attorney's fees and expenses, involved in such
requested assistance.

         7.6 USSC shall by solely responsible to institute and fund any recall,
field corrective action, or the like in circumstances relating to a USSC Royalty
Product defect or failure which requires such action as determined by the FDA,
any International Regulatory Agency or any other similar authority within or
outside


                                       24


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   25
the United States, or by USSC or as otherwise may be required pursuant
to applicable Laws. In such circumstances, the actual retrieval of the USSC
Royalty Products will be the responsibility of USSC and handled by USSC or third
Persons authorized by USSC. Neoprobe shall assist USSC in any such recall, field
corrective action, or the like and shall be reimbursed by USSC for Neoprobe's
out of pocket costs, other than attorney's fees and expenses, involved in such
requested assistance.

         7.7 Neoprobe represents, warrants and covenants that (i) in connection
with any Neoprobe Product sold to customers, it will have and will continue to
have and maintain, effective Regulatory Approvals to manufacture and sell
Neoprobe Products in the Territory, to the extent required by Law, and shall
provide a copy of such Regulatory Approvals to USSC, and (iii) that the
submissions made by Neoprobe to obtain or maintain Regulatory Approval shall be
made in good faith and contain accurate and complete data and information
regarding the Neoprobe Products as required by applicable Laws. Neoprobe
warrants and covenants that no Neoprobe Products delivered by it, or on its
behalf, to customers will be adulterated or misbranded at the time of delivery
within the meaning of the Act.

         7.8 USSC represents and warrants that (i) it shall comply with all
applicable Laws in its advertising, promotion and sale of Neoprobe Products,
(ii) it shall promote the Neoprobe Product only within the approved indication;
and (iii) all advertising, detail aids, promotional materials and sales
brochures used by it to market the Neoprobe Product shall be approved by
Neoprobe. Neoprobe represents and warrants that (i) it shall comply with all
applicable Laws in its advertising, promotion and sale of Neoprobe Products,
(ii) it shall advise USSC of the approved indication, and (iii) Neoprobe's
approval of USSC advertising, detail aids, promotional materials and sales
brochure for Neoprobe Products, and all advertising, detail aids, promotional
materials and sales brochures prepared by Neoprobe for Neoprobe Products, shall
be consistent with all applicable Regulatory Approvals.


                                       25



Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   26
                       ARTICLE 8 - INVENTIONS AND PATENTS

         8.1 The Parties each acknowledge that the other Party has developed or
acquired methods, processes and apparatus relating to their respective fields of
endeavor. Notwithstanding anything in this Agreement to the contrary, each Party
shall retain all right and title in and to such methods, processes and apparatus
developed or owned on their respective parts prior to the Effective Date. During
the term of this Agreement, inventions by Neoprobe or USSC shall be treated as
follows:
                  (i) Inventions, whether or not patentable, which are conceived
and/or reduced to practice (i) solely by or on behalf of USSC based on Neoprobe
Confidential Information, or (ii) solely by or on behalf of Neoprobe based on
Neoprobe Confidential Information, **** shall be owned by Neoprobe 
(collectively, "Neoprobe Inventions"); and
                  (ii) Invention, whether or not paten table, which are
conceived and/or reduced to practice (i) solely by or on behalf of USSC based on
USSC Confidential Information, (ii) solely by or on behalf of Neoprobe based on
USSC Confidential Information, **** shall be owned by USSC (collectively, 
"USSC Inventions").


         8.2

         (a) Neoprobe shall have sole right and shall have sole responsibility
at its sole cost to obtain and maintain all Patents involving or related to
Neoprobe Products. Neoprobe shall keep USSC advised of the status of all such
Patents and shall communicate with USSC with respect to all proposed filings and
applications with as much time as possible for USSC to determine whether it


                                       26


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   27
desires copies of such proposed filing and applications, such copies to be at
USSC's cost and expense and to provide comments thereon prior to the filing
thereof as well as a copy of all Patents upon the issuance thereof.

         (b) **** In such event, USSC shall keep Neoprobe advised of the status
of all such Patents and shall provide Neoprobe with a copy of all proposed
filings and applications with as much time as possible for Neoprobe to provide
comments thereon prior to the filing thereof as well as a copy of all Patents
upon the issuance thereof. In addition, in such event (i) Neoprobe agree to
execute and deliver all documents which USSC may deem necessary or desirable in
connection with USSC's prosecution efforts, and (ii) if USSC thereafter decides
to abandon a Patent, it shall give notice of such decision to Neoprobe and
provide Neoprobe the opportunity to assume responsibility for such Patent.

         8.3 If USSC or Neoprobe receives notice of an Action by a third Person
alleging infringement of such third Person's rights in connection with the
manufacture, use or sale of a Neoprobe Product by Neoprobe, the Party receiving
such notice shall promptly notify the other Party. **** USSC shall keep Neoprobe
advised of the status of such Action and shall provide USSC with a copy of all
litigation papers received or prepared involving or relating thereto. Neoprobe
shall fully cooperate with USSC in its defense of such infringement Action ****


                                       27


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   28
**** Neoprobe shall also have the right in its discretion to join in the
defense of any such Action ****

         8.4 The Parties shall each give prompt written notice to the other of
any apparent infringement discovered by it with respect to any Patent. Such
notice shall set forth the facts of the apparent infringement in reasonable
detail to the extent then known to the notifying Party. Should either Neoprobe
or USSC desire that an Action be brought against third party infringers to
enforce a Patent, the Party shall notify the other Party. **** USSC shall keep
Neoprobe advised of the status of such Action **** and shall provide a copy of
all litigation papers received or prepared involving or relating thereto.
Neoprobe shall cooperate with USSC in connection with any such Action ****
Neoprobe shall have the right in its discretion to join in any such Action ****

         8.5 The provisions of this Article 8 shall survive termination of this
Agreement.


                     ARTICLE 9 - INDEMNIFICATIONS; INSURANCE

         9.1 (a) Neoprobe shall be liable for and shall indemnify and hold USSC,
its Affiliates and permitted assignees, and each of their respective directors,
officers, employees, agents and representatives (collectively, "USSC


                                       28


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   29

   
Indemnities") harmless from and against any liability, damage or loss and from
any judgments, awards, claims, Action, demands, recoveries or expenses which (i)
arise out of Neoprobe's breach of this Agreement or of any representation or
warranty made to USSC under this Agreement, or (ii) result from the negligent
acts or willful malfeasance on the part of Neoprobe or Neoprobe's employees or
agents, or (iii) arising out of any tort claim, worker's compensation claims or
other employment related claims of any agents or employees of Neoprobe; or (iv)
to the extent caused by a Neoprobe Product, except (aa) to the extent caused by
an act or omission of USSC or its agents, or (bb) arising out of or incident to
any misrepresentation or any breach of any warranty or covenant of USSC
hereunder or any default in the observance or performance of any term or
provision to be observed or performed by USSC hereunder.

         (b) USSC shall be liable for and shall indemnify and hold Neoprobe, its
Affiliates and permitted assignees, and each of their respective directors,
officers, employees, agent and representatives (collectively, "Neoprobe
Indemnities") harmless from and against any liability, damage or loss and from
any judgment, awards, claims, Action, demands, recoveries or expenses which (i) 
arise out of USSC's breach of this Agreement or of any representation or 
warranty made to Neoprobe under this Agreement, or (ii) result from the 
negligent acts or willful malfeasance on the part of USSC or USSC's employees 
or agents including, without limitation, in promoting a Neoprobe Product in a 
manner inconsistent with the Neoprobe Product's labeling, except as to 
Promotional Materials approved by Neoprobe, or (iii) arising out of any tort 
claim, worker's compensation claims or other employment related claims of any 
agents or employees of USSC; or (iv) to the extent caused by a USSC Royalty 
Product, except (aa) to the extent caused by an act or omission of Neoprobe or 
its agents, or (bb) arising out of or incident to any misrepresentation or any 
breach of any warranty or covenant of Neoprobe hereunder or any default in the 
observance or performance of any term or provision to be observed or performed 
by USSC hereunder.
    


                                       29


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   30
         (c) If any lawsuit concerning Neoprobe Products, USSC Royalty Products
or the transactions contemplated by this Agreement is brought by or on behalf of
a third party against Neoprobe and/or USSC, in such event Neoprobe and USSC
shall reasonably consult concerning the handling of such matter. However, this
obligation to consult shall not affect the liabilities and obligations imposed
by this Section 9.1.

         (d) On execution of this Agreement, each party shall maintain
comprehensive general liability insurance, including product liability insurance
with broad form vendors coverage, with insurance carriers reasonably acceptable
to the other party on a claims made basis in an amount not less than ****.
Following the execution of this Agreement, Neoprobe shall make reasonable
efforts to increase the amount of such insurance to ****. Neoprobe shall
consider increases in the amount of such insurance beyond **** based on its
business judgment exercised in a reasonable and prudent manner. Such insurance
shall have a combined single limit for bodily injury and property damage per
occurrence and in the aggregate in the aforementioned amounts. Such insurance
may contain provision for a deductible or self-insured retention ****. Such
insurance shall include the other party as an additional named insured as its
interest may appear. Commencing with Regulatory Approval to sell a Neoprobe
Product, each party shall furnish to the other party a certificate of insurance
evidencing such coverage with thirty days' written notice to the other party of
cancellation or material change. Nothing set forth herein in this Section 9.1(d)
is intended to substitute for the indemnity rights of the parties set forth in
this Agreement.

         9.2 Promptly after receipt by a Party indemnified pursuant to this
Agreement of the commencement of any Action against such indemnified Party in
respect of which indemnity or reimbursement may be sought against the
indemnifying Party hereunder, such indemnified Party shall promptly notify the
indemnifying Party in writing of the commencement of the Action, but the failure
to do so notify the indemnifying Party shall not relieve it of any liability


                                       30


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   31
which it may have to any such indemnified Party unless such a failure
substantially prejudices the rights of the indemnifying Party hereunder. If any
such action shall be brought against any indemnified Party and it shall notify
the indemnifying Party of the commencement thereof, the indemnifying Party shall
be entitled to participate therein, and to the extent it so desires, jointly
with any other indemnifying Party similarly notified, to control the defense
thereof, with counsel reasonably satisfactory to such indemnified Party. After
notice is given by the indemnifying Party to the indemnified Party of its
election to so assume the defense thereof, the indemnified Party may participate
in the defense thereof, but the indemnifying Party shall not be liable to such
indemnified party under this Section 9.2 for any legal or other expenses
subsequently incurred by such indemnified Party in connection with its
participation in the defense thereof other than out of pocket costs and expenses
of the indemnified party (excluding legal costs and expenses) in connection with
assistance rendered to the indemnifying party at the specific request of the
indemnifying Party.

         9.3 The provisions of this Article 9 shall survive termination of this
Agreement.


                 ARTICLE 10 NONCOMPETE;EXCLUSIVITY; STAND STILL

         10.1 During the term of this Agreement, Neoprobe shall not, directly or
indirectly, without USSC's prior written consent, in its sole and absolute
discretion, (a) market or solicit, or permit, encourage or assist third parties
to market or solicit, the sale or lease of Neoprobe Products in the Territory,
other than through USSC, or (b) market or sell, or permit, encourage or assist
third parties to market or solicit, the sale of products similar to or
competitive with USSC Royalty Products.

         10.2 During the term of this Agreement, USSC shall have the right to
market and sell USSC Royalty Products in connection with Neoprobe Products but
shall not, directly or indirectly, without Neoprobe's prior written consent, in


                                       31


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   32
its sole absolute discretion, market or sell, or permit encourage, or assist
third parties to market or sell, products in the Territory similar to or
competitive with Neoprobe Products.

         10.3  ****

         10.4 USSC hereby agrees to the ownership and control restrictions set
for in Exhibit 10.4.


                       ARTICLE 11 - RIGHT OF FIRST REFUSAL

         11.1 Neoprobe hereby grants to USSC the below rights of first refusal
for Rights Technologies set forth in this Article 11. In accordance with such
rights of first refusal, Neoprobe agrees not to transfer, by sale, license or
otherwise, any interest in any of the Rights Technology to any third Person,
except pursuant to this Article 11.

         11.2 If and when (but not prior to the date that) Neoprobe has produced
a prototype and established a development plan and budget, clinical protocols
and a market study with respect to a Rights Technology, Neoprobe shall provide
USSC with a copy of each such document and other data relating thereto. ****
following USSC's receipt of all such documents and data, USSC and Neoprobe shall
negotiate exclusively, confidentially and in good faith for the license to USSC
of such Rights Technology (the "First Exclusive Negotiation Period") on
commercially reasonable terms and conditions. During the First Exclusive
Negotiation Period, Neoprobe shall provide USSC with any additional information
and data concerning commercialization of such Rights Technology which may come
into its possession or control during the First Exclusive Negotiation Period. If
the Parties reach agreement with respect to such Rights Technology including the
agreement by USSC to assume all development costs for such Rights Technology,
Neoprobe shall grant to USSC an exclusive worldwide license to market such Right
Technology and all


                                       32


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   33
Improvements thereto, ****.

         11.3 If and when Neoprobe shall commence Phase II clinical trials as
that term is interpreted by the FDA, with respect to a Rights Technology,
Neoprobe shall provide USSC with a copy of the protocols, the trial results and
other data relating to the development of the Rights Technology, as the same
becomes available, until the completion of such Phase II clinical trials. ****
following USSC's receipt of all such documents and data including the results of
the completed Phase II clinical trials, USSC and Neoprobe shall negotiate
exclusively, confidentially and in good faith for the license to USSC of such
Rights Technology (the "Second Exclusive Negotiation Period") on commercially
reasonable terms and conditions. During the Second Exclusive Negotiation Period,
Neoprobe shall provide USSC with any additional information and data concerning
commercialization of such Rights Technology which may come into its possession
or control during the Second Exclusive Negotiation Period. If the Parties reach
agreement with respect to such Rights Technology, Neoprobe shall grant to USSC
an exclusive worldwide license to market such Rights Technology and all
Improvements thereto. If the Parties are unable to reach agreement with respect
to such Rights Technology, Neoprobe would be free to enter into a transaction
****.


                        ARTICLE 12 - TERM AND TERMINATION

         12.l This Agreement shall remain in full force and effect from the date
hereof until the date which is five (5) years from the date the last of the
conditions set forth in Section 4.1(b) above shall have been met, unless earlier
terminated pursuant to this Article 12 (the "Term").


                                       33


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   34
         12.2 USSC shall have a paid up option to renew this Agreement for
successive five (5) year terms on the same terms and conditions as set forth in
this Agreement with payments by USSC to Neoprobe limited to Research and
Development Payments and the Royalty as provided hereinabove in this Agreement
(the "Renewal Option"). The Renewal Option shall be exercisable by notice given
by USSC to Neoprobe no later than twelve (12) months prior to the end of the
Term and each renewal term.

   
         12.3 This Agreement may be terminated prior to the end of the term of
this Agreement as follows: 
         (a) by either Party, in the event the other Party files any petition in
a bankruptcy or similar proceeding or, if the other Party has a petition in a
bankruptcy or similar proceeding filed against it and such proceeding continues
unstayed after forty five (45) days after the filing thereof;
         (b) by either Party, in the event the other Party becomes insolvent or
makes an assignment for the benefit of its creditors; 
         (c) by either Party, in the event a Force Majeure Event (defined below)
prevents the other Party from performing for more than ninety (90) days; 
         (d) by either Party, in the event the other Party refuses to perform or
shall materially breach or materially fail in the observance or performance of
any representation, warranty, covenant or obligation under this Agreement
following notice of such refusal, breach or failure; provided however, that the
Party receiving such notice shall have thirty (30) days after receiving notice
to cure the refusal, breach or failure. In the event such breach or failure is
cured, the notice shall be of no effect. In the event such refusal, breach or
failure is not cured, this Agreement shall then terminate at the end of such
thirty (30) day period. Notwithstanding the foregoing, neither party shall not
be deemed in default hereof for failure to pay any amount to the other party
providing it is diligently and in good faith contesting such amount by an
Action. 
         (e) by USSC, in the event Neoprobe refuses or fails to supply units of
Neoprobe Product to customers for any consecutive three (3) month period or
refuses or fails to perform or cause to be performed the installation, warranty,
maintenance or other customer services for a Neoprobe Product; 
    


                                       34


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   35
         (f) by USSC, in the event Neoprobe does not achieve the regulatory
approvals described in Section 4.1(b); and
         (g) by USSC, without cause on twelve (12) months written notice to
Neoprobe.

         12.4 In the event of termination of this Agreement, each Party shall
fulfill all obligations existing as of the effective date of termination and
shall supply all open customer orders and payment for Neoprobe Product and USSC
Royalty Products that may be due under this Agreement. Notwithstanding, USSC
shall not be obligated to pay Neoprobe the Additional Licensee Fees set forth in
Section 4.1(b) in the event Neoprobe achieves either or both of such regulatory
approvals subsequent to the date that USSC gives notice to Neoprobe of
termination of this Agreement, unless USSC shall in its discretion solicit
orders for Neoprobe Products in such portion of the Territory covered by such
regulatory approval during the period between the date notice of termination is
given to Neoprobe and the effective termination date of this Agreement.

         12.5 In the event of termination of this Agreement by Neoprobe pursuant
to Section 12.3(d) above, USSC shall grant Neoprobe **** with respect to the
manufacture, marketing and sale by Neoprobe of USSC Royalty Products solely in
connection with Neoprobe's sale of Neoprobe Products, but only as to USSC
Royalty Products which are commercially offered for sale by USSC as of such
grant date. Notwithstanding **** set forth in this Section 12.5., Neoprobe shall
be responsible for obtaining any Regulatory Approvals for Neoprobe's
manufacture, use and sale of USSC Royalty Products and Neoprobe shall not use
any USSC trademark or otherwise refer to USSC in connection with its
manufacture, use or sale of such USSC Royalty Products.


                          ARTICLE 13 - CONFIDENTIALITY


                                       35


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   36
         13.1 Each Party represents, warrants and covenants that it has not,
directly or indirectly, disclosed and agrees that it shall not , directly or
indirectly, disclose to any third person or entity either during the term of
this Agreement or for a period of five (5) years subsequent to the termination
of this Agreement, (a) any Confidential Information concerning the other Party
disclosed in accordance with this Agreement; or (b) the terms or substance of
this Agreement except as required by law or legal process in the reasonable
opinion of counsel to the disclosing Party; provided that prior to any such
disclosure the disclosing Party shall notify the other Party of such proposed
disclosure with as much prior notice as is reasonably possible and shall not
take any action to prevent the other Party from taking any legal action as it
deems necessary or desirable to prevent or limit any such disclosure.

         13.2 Notwithstanding Section 13.1, each Party may disclose Confidential
Information received pursuant to this Agreement to its directors, officers,
employees, consultants, attorneys and accountants provided that such persons and
entities are obligated to hold the Confidential Information in confidence. Each
Party covenants that it shall exercise the same degree of care with respect to
the other Party's Confidential Information as it would its own Confidential
Information.

         13.3 Upon termination of this Agreement, each Party shall, upon the
request of the other Party, return all documents received by it from the other
Party which contain the other Party's Confidential Information or destroy all of
such documents and confirm in writing the destruction thereof to the other
Party, except that one copy thereof may be retained solely for archival purposes
in the files of the counsel for the Party.

         13.4 The provisions of this Article 13 shall survive termination of
this Agreement.


             ARTICLE 14 - REPRESENTATIONS, WARRANTIES AND COVENANTS


                                       36


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   37
         14.1 Each Party represents, warrants and covenants to the other Party
that (i) the performance by such Party of its obligations under this Agreement
will not result in a violation or breach of, and not conflict with or constitute
a default under, its Certificate of Incorporation or other incorporation
documents, corporate bylaws or any contract, commitment, agreement or other
obligation to which such Party or any of its Affiliates is a party or by which
any of them is bound; and (ii) there is no Action pending or currently
threatened against it or any of its Affiliates which, if adversely determined,
would restrict or limit such Party's right to enter into this Agreement,
transfer the rights or carry out its obligations under this Agreement.

         14.2  Neoprobe represents, warrants and covenants to USSC:
(i)to the best of Neoprobe's knowledge and belief, as of the date of this
Agreement, Exhibit 14.2 attached hereto is a true and complete list of all
contracts, commitments and agreements pursuant to which Neoprobe or its
Affiliates owns, licenses or has any right, title or interest in intellectual
property involving or relating to the RIGScan System (collectively, "Material
IPRs"); (ii) Neoprobe is, and, during the term of this Agreement, shall remain
in compliance in all material respects with the Material IPRs; (iii) to the best
of Neoprobe's knowledge and belief, as of the effective date of this Agreement,
Neoprobe has not received a notice of an Action by a third Person alleging a
breach or violation of a Material IPR, infringement of a third Person's
intellectual property rights involving or relating to a Material IPR or
challenging the ownership, validity or enforceability of any Material IPR; (iv)
to the best of Neoprobe's knowledge, (aa) each Person which sublicenses a
Material IPR to Neoprobe (collectively, "Licensors") is in compliance in all
material respect with the related license (collectively, "Licenses") to which
such sublicense relates, and (bb) no Licensors has received a notice of an
Action by a third Person alleging a breach or violation of a License,
infringement of a third Person's intellectual rights involving or relating to
the License, or challenging the ownership, validity or enforceability of a
License or intellectual property covered thereby; and (v) Neoprobe is, and
during the term of this Agreement, shall remain in compliance


                                       37


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   38
in all material respects with the terms set forth in that certain agreement
entitled "Patent License Agreement--Exclusive" ("NCI Agreement") between the
National Cancer Institute and Dow Chemical Company ("Dow") dated in January,
1993 to the extent such terms are applicable to Neoprobe, or as to which
Neoprobe is bound, such that Neoprobe's intellectual property rights as
sublicensee to the NCI Agreement are, and shall remain, exclusive, such terms
being imposed upon Neoprobe pursuant to the terms of such NCI Agreement and as
sublicensee thereof pursuant to that certain agreement entitled "Technology
Transfer Agreement" between Dow and Neoprobe dated July 29, 1992.

         14.3 Promptly following the execution of this Agreement, the parties
shall discuss that certain existing agreement between Neoprobe and **** and
Neoprobe Corporation ****. If following such discussion USSC shall desire that
Neoprobe ****, USSC shall notify Neoprobe thereof and, in such event, Neoprobe
shall cause **** to promptly ****. Notwithstanding the foregoing (i) Neoprobe
shall not be required to **** in its entirety in accordance with the foregoing
but only as to the ****, (ii) Neoprobe's  **** in accordance with the foregoing
shall not be deemed a violation of Section 14.2(ii) set forth above, and (iii)
as to any intellectual property owned by Neoprobe arising from the ****
(collectively, "****"), USSC is hereby granted the exclusive, worldwide right
and license during the term of this Agreement to make, have made, use and sell
products, and components and related accessories, which incorporate ****. The
provisions of this Agreement relating to USSC Royalty Products shall also be
applicable to products incorporating ****.


                           ARTICLE 15 - FORCE MAJEURE

         15.1 If either Party is prevented from performing any of its
obligations hereunder due to any cause which is beyond the non-performing
Party's reasonable control, including fire, explosion, floor, or other acts of
God; acts,


                                       38


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   39
regulations, or laws of any government; war or civil commotion; strike, lock-out
or labor disturbances; or failure of public utilities or common carrier(a "Force
Majeure Event"), such non-performing Party shall promptly give notice thereof to
the other party and shall use its best efforts to cure or correct any such Force
Majeure Event and to resume performance of its affected obligations as soon as
possible. ****


                           ARTICLE 16 - MISCELLANEOUS

         16.1 This Agreement shall be binding upon and shall inure to the
benefit of each of the Parties hereto, and their respective successors and
permitted assigns as hereinafter set forth in this Section 16.1. Neither Party
shall transfer or assign this Agreement, in whole or in part, nor any of their
respective rights and obligations under this Agreement without the prior written
consent of the other Party; except that USSC may, without such consent, assign
this Agreement to a Affiliate of USSC provided USSC remain liable for the
performance thereof, and except an assignment, transfer or disposition is to a
successor to all of the business and assets of the transferor, provided that,
such successor shall in any event agree in writing with the other Party to
assume all obligations of the transferor under this Agreement in a manner
satisfactory to the other Party, provided that in no event shall such successor
be Johnson & Johnson, its Ethicon, Inc. Affiliate, or any other Affiliate of
either thereof.

         16.2 All notices, and other communications required or called for under
this Agreement shall be in writing, shall be transmitted by overnight U.S. mail,
postage prepaid, or by certified or registered U.S. Mail, return receipt
requested, postage prepaid or by overnight Federal Express or another nationally
recognized courier serviced (billed to sender) and shall be deemed delivered
when received by the Party to whom it is addressed at:


                                       39


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   40
If to Neoprobe:                             If to USSC:
Neoprobe Corporation                        United States Surgical Corporation
425 Metro Place North, Suite 400            150 Glover Avenue
Dublin, Ohio  43017-1367                    Norwalk, CT  06856
Attn.: President                            Attn.: Thomas R. Bremer
                                            Senior Vice President and
                                            General Counsel

         16.3 This Agreement supersedes all prior discussions, negotiations, and
agreements between the Parties including, without limitation, any
confidentiality agreement heretofore entered into between the parties, but only
as to matters occurring after the date of the execution of this Agreement by
both Parties. This Agreement cannot be altered or amended except by an agreement
in writing signed by the Parties.

         16.4 No previous course of dealing or performance or usage of trade not
specifically set forth in this Agreement shall be admissible to explain, modify
or contradict this Agreement. Either Party's failure to require performance by
the other of any provisions hereof shall, in no way, be deemed a waiver or
affect the right of either Party to require such performance at any time
thereafter.

         16.5 This Agreement shall not constitute either Party as an employee,
agent, partner or legal representative of the other Party for any purpose, or
give either Party any right to supervise or direct the functions of the other
Party. Neither Party shall have authority to act for or obligate the other Party
in any way or to extend any representation or warranty on behalf of the other
Party. Each Party agrees to perform under this Agreement solely as an
independent contractor and shall not hold itself out as an employee or agent of
the other Party in any sense. Each Party agrees not to permit its employees or
agents to do anything which might be construed or interpreted as acts of the
other Party. Each Party agrees that the other Party shall not be responsible for
any acts or omissions by it or its directors, officers, employees and agents and
shall indemnify and hold harmless the other Party from and against all losses,


                                       40


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   41
damages, claims, judgments, and costs (excluding attorneys' fees and expenses)
claimed or rendered against such other Party on account of acts or omissions by
such Party, its directors, officers, employees and agents.

         16.6 Neither Party shall originate any publicity, news release or other
announcement, written or oral, relating to the terms and conditions of this
Agreement without the prior written consent of the other Party ****.

         16.7 If any provisions of this Agreement should be or become fully or
partly invalid or unenforceable for any reason whatsoever or violate any
applicable law, this Agreement is to be considered divisible as to such
provision and such provision is to be deleted from this Agreement, and the
remainder of this Agreement shall be deemed valid and binding as if such
provision were not included herein. There shall be substituted for any such
provision deemed to be deleted a suitable provision which, as far as legally
possible, comes nearest to what the Parties desired according to the sense and
purpose of this Agreement had this point been considered when concluding this
Agreement .

         16.8 This Agreement shall be governed by and construed in accordance
with the internal laws of the State of **** applicable to contracts entered
into and to be performed entirely within the State of **** without reference
to its conflict of laws provisions. Any controversy or claim arising out of or
relating to this Agreement, or the breach thereof, shall be exclusively settled
by any federal or state court located in the State of **** and the Parties
irrevocably submit to the exclusive jurisdiction of such courts and waive any
and all objections to jurisdiction, venue or service that they may have under
the laws of the State of **** or otherwise in those courts in any such
Action.

         16.9 The Article headings included in this Agreement are for reference
purposes only and shall not affect the meaning or interpretation of this
Agreement.


                                       41


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   42
         16.10 This Agreement may be executed in two counterparts, each of which
shall be deemed to be an original instrument, but both such counterparts
together shall constitute but one agreement.


                                       42


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   43
         IN WITNESS WHEREOF, the Parties have caused this Agreement to be signed
by their respective corporate officers as of the date first above written.

                                    NEOPROBE CORPORATION

                                    By:       s/David C. Bupp
                                       -------------------------------
                                    Name:     President, COO
                                         -----------------------------
                                    Title:    DAVID C. BUPP
                                          ----------------------------


                                    UNITED STATES SURGICAL CORPORATION

                                    By:       s/Elton Nahum
                                       -------------------------------
                                    Name:     ELTON NAHUM
                                         -----------------------------
                                    Title:    Vice President, Strategic Planning
                                          ----------------------------
                                              & Business Development
                                          ----------------------------

EXHIBITS

A-1      Patents
A-2      Trademarks
B        Warranty
2.1      Trademark License
3.6      Neoprobe Product Pricing and Non Price Terms of Sale
4.3      USSC Commissions
10.3     Sales Penetration Levels
10.4     Ownership and Control Restrictions
14.2     Material Intellectual Property Rights


                                       43


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   44
                                                                     EXHIBIT A-1

                                     PATENTS




                                       44


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   45


                  NEOPROBE CORPORATION RIGS(R) PATENT PORTFOLIO

                                  CONFIDENTIAL

                               September 20, 1996

                            MUELLER AND SMITH, L.P.A.

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

Method for Locating, Differentiating, and Removing Neoplasms
Attorney Docket No.:  NEO 2-003-3

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>      <C>                               <C>                                 <C>
         4,782,840                          November 8, 1988                    United States
</TABLE>

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

===============================================================================
Detector and Localizer for Low Energy Radiation Emissions
Attorney Docket No.:  NEO 2-014

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>      <C>                               <C>                                 <C>
         4,801,803                          January 31, 1989                    United States
</TABLE>

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

===============================================================================
Detector and Localizer for Low Energy Radiation Emissions
Attorney Docket No.:  NEO 2-014-3

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>      <C>                               <C>                                 <C>
         4,893,013                          January 9, 1990                     United States
         P3870502.8                         April 29, 1992                      Germany
         284,542                            April 29, 1992                      Spain
         284,542                            April 29, 1992                      France
         284,542                            April 29, 1992                      Great Britain
         284,542                            April 29, 1992                      Italy
         284,542                            April 29, 1992                      Liechtenstein
         284,542                            April 29, 1992                      Sweden
         1,337,441                          October 24, 1995                    Canada
         1,337,440                          October 24, 1995                    Canada
</TABLE>


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


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   46
Neoprobe Corporation RIG(R) Patent Portfolio                    MUELLER & SMITH
September 20, 1996                                                 CONFIDENTIAL
Page 2



===============================================================================
Gamma Radiation Detector with Enhanced Signal Treatment
Attorney Docket No.:  NEO 2-030

<TABLE>
<CAPTION>
         PATENT NO.                       ISSUE DATE                       COUNTRY
         ----------                       ----------                       -------

<S>                                       <C>                             <C>
         4,889,991                        December 26, 1989                United States
         613,795                          September 21, 1989               Australia
         0369927                          September 21, 1989               Austria
         1,313,429                        February 20, 1993                Canada
         0369927                          September 21, 1989               France
         P68907697-5                      September 21, 1989               Germany
         0369927                          September 21, 1989               Great Britain
         0369927                          September 21, 1989               Greece
         0369927                          September 21, 1989               Italy
         0369927                          September 21, 1989               Luxembourg
         0369927                          September 21, 1989               Netherlands
         0369927                          September 21, 1989               Spain
         89630157-9                       September 21, 1989               Sweden
         0369927-4                        September 21, 1989               Switzerland
         91,754                           May 23, 1993                     Israel
</TABLE>

<TABLE>
<CAPTION>
         APPLICATION NO.                  FILING DATE                  COUNTRY             STATUS
         ---------------                  -----------                  -------             ------

<S>      <C>                             <C>                          <C>                <C>
         248969/89                        September 25, 1989           Japan               pending
         13830/1989                       September 23, 1989           South Korea         pending
</TABLE>

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


===============================================================================
Detector and Localizer for Low Energy Radiation Emissions
Attorney Docket No.:  NEO 2-037-3

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                        <C>                                 <C>
         5,070,878                          December 10, 1991                   United States
         618,403                            September 21, 1989                  Australia
         1,315,424                          March 30, 1993                      Canada
         91,754                             May 23, 1993                        Israel
         0369927                            July 21, 1993                       European Patent*
</TABLE>

         *European application has been allowed and we are in the process of
          entering the national phase.

<TABLE>
<CAPTION>

         APPLICATION NO.            FILING DATE                   COUNTRY               STATUS
         ---------------            -----------                   -------               ------

<S>                                <C>                           <C>                   <C>
         296031/89                  November 14, 1989             Japan                 pending
         16465/1989                 November 13, 1989             South Korea           pending
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   47
Neoprobe Corporation RIG(R) Patent Portfolio                    MUELLER & SMITH
September 20, 1996                                                 CONFIDENTIAL
Page 3


===============================================================================
Detector and Localizer for Low Energy Radiation Emissions
Attorney Docket No.:  NEO 2-037-3A

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                        <C>                                 <C>
         5,151,598                          September 29, 1992                  United States
</TABLE>

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

===============================================================================
Radiation Responsive Laparoscopic Instrument
Attorney Docket No.:  NEO 2-141

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                         <C>                                <C>
         5,429,133                          July 4, 1995                        United States
</TABLE>

<TABLE>
<CAPTION>
APPLICATION NO.            FILING DATE                 COUNTRY                          STATUS
- ---------------            -----------                 -------                          ------

<C>                        <C>                         <C>                             <C>
52594/9E                   December 16, 1993           Australia                        no office action
2,110,857                  December 7, 1993            Canada                           no office action
93630100.1                 December 9, 1993            European Patent Office           no office action
93/344/950                 December 20, 1993           Japan                            no office action
93028464                   December 18, 1993           South Korea                      no office action
940056                     January 3, 1994             Mexico                           no office action
992617                     December 18, 1992           Israel                           pending
</TABLE>

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

===============================================================================
Radiation Responsive Surgical Instrument
Attorney Docket No.:  NEO 2-149

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                        <C>                                 <C>
         5,440,050                          August 15, 1995                     United States
</TABLE>

<TABLE>
<CAPTION>
APPLICATION NO.            FILING DATE                   COUNTRY                        STATUS
- ---------------            -----------                   -------                        ------

<C>                        <C>                         <C>                             <C>
52465/93                   December 16, 1993             Australia                      no office action
2,110,858                  December 7, 1993              Canada                         no office action
93630101.9                 December 9, 1993              European Patent Office         no office action
93/344951                  December 20, 1993             Japan                          no office action
93028465                   December 18, 1993             South Korea                    no office action
940055                     January 3, 1994               Mexico                         no office action
992,622                    December 18, 1992             Israel                         no office action
</TABLE>

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


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   48
Neoprobe Corporation RIG(R) Patent Portfolio                    MUELLER & SMITH
September 20, 1996                                                 CONFIDENTIAL
Page 4


===============================================================================
Crystal Array Based Localizer for Lymph Sampling
Attorney Docket No.:  NEO 2-172

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                         <C>                                 <C>
         5,495,111                          February 27, 1996                   United States
</TABLE>

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

===============================================================================
Fundamental Mode Logic Based Lower Threshold--Upper Limit Discriminator
Attorney Docket No.:  NEO 2-215

<TABLE>
<CAPTION>
PATENT NO.                     ISSUE DATE                     COUNTRY
- ----------                     ----------                     -------

<C>                            <C>                           <C>
5,475,219                      Dec. 12, 1995                  United States
</TABLE>


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

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

****


<TABLE>
<CAPTION>
APPLICATION NO.                   FILING DATE                 COUNTRY                          STATUS
- ---------------                   -----------                 -------                          ------
<C>                               <C>                         <C>                              <C>
542,955                           October 13, 1995            United States                    pending
</TABLE>


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

****

<TABLE>
<CAPTION>
APPLICATION NO.                   FILING DATE                 COUNTRY                          STATUS
- ---------------                   -----------                 -------                          ------
<C>                               <C>                         <C>                              <C>
543,032                          October 13, 1995             United States                    pending
</TABLE>

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

****

<TABLE>
<CAPTION>
APPLICATION NO.                   FILING DATE                 COUNTRY                          STATUS
- ---------------                   -----------                 -------                          ------

<C>                               <C>                         <C>                              <C>
not yet assigned                  June 13, 1996               United States                    new filing
</TABLE>

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


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   49
Neoprobe Corporation RIG(R) Patent Portfolio                    MUELLER & SMITH
September 20, 1996                                                 CONFIDENTIAL
Page 5


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

Radiation Responsive Laparoscopic Instrument
Attorney Docket No.:  NEO 2-141-3
(Joint Invention and Ownership with OSURF)

<TABLE>
<CAPTION>
         PATENT NO.                         ISSUE DATE                          COUNTRY
         ----------                         ----------                          -------

<S>                                         <C>                                 <C>
         5,383,456                          January 24, 1995                    United States
</TABLE>

<TABLE>
<CAPTION>
APPLICATION NO.                   FILING DATE                 COUNTRY                          STATUS
- ---------------                   -----------                 -------                          ------

<S>                             <C>                          <C>                              <C>
not yet assigned                                              Canada                           new filing
not yet assigned                                              Israel                           new filing
951,433                          May 17, 1995                 Mexico                           new filing
</TABLE>

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

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

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

Intra-Operative Biostaging of Patients
Attorney Docket No. ORF 2-003
(Licensed from OSURF)

<TABLE>
<CAPTION>
PATENT NO.                       ISSUE DATE                   COUNTRY
- ----------                       ----------                   -------

<C>                              <C>                          <C>
5,482,040                        January 9, 1996              United States
</TABLE>

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

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

===============================================================================
****

<TABLE>
<CAPTION>
APPLICATION NO.              FILING DATE                    COUNTRY                          STATUS
- ---------------              -----------                    -------                          ------

<C>                          <C>                           <C>                               <C>
114,675                      August 31, 1993 Allowed                                         United States
47461/93                     September 15, 1993             Australia                        no office action
2,107,074                    September 15, 1993             Canada                           no office action
93630068.0                   September 14, 1993             European Patent Office           no office action
93/228520                    September 14, 1993             Japan                            no office action
93018498                     September 15, 1993             South Korea                      no office action
935690                       September 15, 1993             Mexico                           no office action
107005                       September 14, 1993             Israel                           no office action
</TABLE>

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


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   50
Neoprobe Corporation RIG(R) Patent Portfolio                    MUELLER & SMITH
September 20, 1996                                                 CONFIDENTIAL
Page 6


Second Generation Monoclonal Antibodies Having Binding Specificity to TAG-72 and
Human Carcinomas and Methods for Employing the Same
(Sublicensed From NIH via The Dow Chemical Company)

U.S. Pat. No. 5,512,443

Counterparts are pending in Australia, Japan, and The European Patent Office
(according to NIH records).
===============================================================================

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


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   51
            NEOPROBE CORPORATION TRADEMARK REGISTRATIONS/APPLICATIONS
                       FOR RIGS(R) AND RIGSCAN(R) PRODUCTS
                               SEPTEMBER 20, 1996

NEOPROBE
Attorney Docket No.:  NEO 5-017

         "Radiation Detection Probe and Microprocessor-Based Controller and
         Analyzer"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------
<S>                                         <C>                                <C>
         1,534,135                          April 11, 1989                      United States
         1,938,283                          November 28, 1995                   United States
         259040                             June 17, 1994                       Sweden
         151006                             January 28, 1994                    Austria
         541191                             August 1, 1994                      Benelux
         2079214                            September 27, 1994                  Germany
         B1551931                           August 11, 1995                     Great Britain (Class 5)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002090                        November 2, 1993                    Italy
         113414/93                          November 10, 1993                   Japan (Class 5)
         113415/93                          November 10, 1993                   Japan (Class 10)
         38908/93                           November 3, 1993                    S. Korea (Class 10)
         38909/93                           November 3, 1993                    S. Korea (Class 11)
         1787313                            October 29, 1993                    Spain (Class 5)
         1787314                            October 29, 1993                    Spain (Class 9)
         90098                              November 29, 1993                   Israel (Class 5)
         90099                              November 29, 1993                   Israel (Class 9)
</TABLE>


RIGS
Attorney Docket No.:  NEO 5-038

         "Radiopharmaceutical Detection Probe and Microprocessor-based
         Controller and Analyzer"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------
<S>                                         <C>                                 <C>
         1,542,372                          June 6, 1989                        United States
         1,929,657                          October 24, 1995                    United States
         151007                             January 28, 1994                    Austria
         540615                             August 1, 1994                      Benelux
         93489489                           October 26, 1993                    France
         2079213                            September 27, 1994                  Germany
         A1551933                           November 25, 1994                   Gerat Britain (Class 5)
         A1551934                           November 25, 1994                   Great Britain (Class 9)
         90101                              October 5, 1995                     Israel (Class 9)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002091                        November 2, 1993                    Italy
         113412/93                          November 10, 1993                   Japan (Class 5)
         113413/93                          November 10, 1993                   Japan (Class 10)
         38906/93                           November 3, 1993                    S. Korea (Class 10)
         38907/93                           November 3, 1993                    S. Korea (Class 11)
         1787317                            October 29, 1993                    Spain (Class 5)
         1787318                            October 29, 1993                    Spain (Clas 9)
         9310118                            October 27, 1993                    Sweden
         90100                              November 29, 1993                   Israel (Class 5)
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   52
Neoprobe Corporation
Trademark Registrations/Applications
September 20, 1996
Page 2


RIGSCAN
Attorney Docket No. NEO 5-163

         "Radiolabelled Pharmaceutical Preparation for Locating Neoplastic
         Tissue"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------

<S>                                         <C>                                 <C>
         1,893,526                          May 9, 1995                         United States
         11008                              January 28, 1994                    Austria
         540614                             August 1, 1994                      Benelux
         93489490                           October 26, 1993                    France
         2079212                            September 27, 1994                  Germany
         1787315                            April 20, 1994                      Spain
         B1551935                           October 14, 1994                    Great Britain (Class 5)
         B1551936                           October 14, 1994                    Great Britain (Class 9)
         90102                              October 5, 1995                     Israel (Class 5)
         90103                              October 5, 1995                     Israel (Class 9)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002092                        November 2, 1993                    Italy
         113410/93                          November 10, 1993                   Japan (Class 5)
         113411/93                          November 10, 1993                   Japan (Class 10)
         38910/93                           November 3, 1993                    S. Korea (Class 10)
         38911/93                           November 3, 1993                    S. Korea (Class 11)
         1787316                            October 29, 1993                    Spain (Class 9)
         9310119                            October 27, 1993                    Sweden (Class 5)
</TABLE>


AUDIBLE TONE SEQUENCE
Attorney Docket No. NEO 2-203US

         "A sequence of audible tones of successively increasing frequencies
from minimum to maximum values broadcast to produce a unique sound"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                               COUNTRY
         --------                           ----                               -------
<S>                                         <C>                                <C>
         1,959642                           March 5, 1996                      United States
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   53
                                                                     EXHIBIT A-2

                                   TRADEMARKS


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   54
            NEOPROBE CORPORATION TRADEMARK REGISTRATIONS/APPLICATIONS
                               SEPTEMBER 25, 1996
                            MUELLER AND SMITH, L.P.A.
NEOPROBE
Attorney Docket No.:  NEO 5-017

         "Radiation Detection Probe and Microprocessor-Based Controller and
         Analyzer"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------

<S>                                        <C>                                 <C>
         1,534,135                          April 11, 1989                      United States
         1,938,283                          November 28, 1995                   United States
         259040                             June 17, 1994                       Sweden
         151006                             January 28, 1994                    Austria
         541191                             August 1, 1994                      Benelux
         2079214                            September 27, 1994                  Germany
         B1551931                           August 11, 1995                     Great Britain (Class 5)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002090                        November 2, 1993                    Italy
         113414/93                          November 10, 1993                   Japan (Class 5)
         113415/93                          November 10, 1993                   Japan (Class 10)
         38908/93                           November 3, 1993                    S. Korea (Class 10)
         38909/93                           November 3, 1993                    S. Korea (Class 11)
         1787313                            October 29, 1993                    Spain (Class 5)
         1787314                            October 29, 1993                    Spain (Class 9)
         90098                              November 29, 1993                   Israel (Class 5)
         90099                              November 29, 1993                   Israel (Class 9)
</TABLE>



RIGS
Attorney Docket No.:  NEO 5-038

         "Radiopharmaceutical Detection Probe and Microprocessor-based
         Controller and Analyzer"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------

<S>                                        <C>                                 <C>
         1,542,372                          June 6, 1989                        United States
         1,929,657                          October 24, 1995                    United States
         151007                             January 28, 1994                    Austria
         540615                             August 1, 1994                      Benelux
         93489489                           October 26, 1993                    France
         2079213                            September 27, 1994                  Germany
         A1551933                           November 25, 1994                   Gerat Britain (Class 5)
         A1551934                           November 25, 1994                   Great Britain (Class 9)
         90101                              October 5, 1995                     Israel (Class 9)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002091                        November 2, 1993                    Italy
         113412/93                          November 10, 1993                   Japan (Class 5)
         113413/93                          November 10, 1993                   Japan (Class 10)
         38906/93                           November 3, 1993                    S. Korea (Class 10)
         38907/93                           November 3, 1993                    S. Korea (Class 11)
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   55
<TABLE>
<S>                                        <C>                                 <C>
         1787317                            October 29, 1993                    Spain (Class 5)
         1787318                            October 29, 1993                    Spain (Clas 9)
         9310118                            October 27, 1993                    Sweden
         90100                              November 29, 1993                   Israel (Class 5)
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   56
RIGSCAN
Attorney Docket No. NEO 5-163

         "Radiolabelled Pharmaceutical Preparation for Locating Neoplastic
         Tissue"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------

<S>                                        <C>                                 <C>
         1,893,526                          May 9, 1995                         United States
         11008                              January 28, 1994                    Austria
         540614                             August 1, 1994                      Benelux
         93489490                           October 26, 1993                    France
         2079212                            September 27, 1994                  Germany
         1787315                            April 20, 1994                      Spain
         B1551935                           October 14, 1994                    Great Britain (Class 5)
         B1551936                           October 14, 1994                    Great Birtain (Class 9)
         90102                              October 5, 1995                     Israel (Class 5)
         90103                              October 5, 1995                     Israel (Class 9)

         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------
         T093C002092                        November 2, 1993                    Italy
         113410/93                          November 10, 1993                   Japan (Class 5)
         113411/93                          November 10, 1993                   Japan (Class 10)
         38910/93                           November 3, 1993                    S. Korea (Class 10)
         38911/93                           November 3, 1993                    S. Korea (Class 11)
         1787316                            October 29, 1993                    Spain (Class 9)
         9310119                            October 27, 1993                    Sweden (Class 5)
</TABLE>



RIGS/ACT
Attorney Docket No. NEO 5-201US

         "Pharmaceutical Therapeutic Preparation for Cancer"

<TABLE>
<CAPTION>
         APPLICATION NO.                    DATE                                COUNTRY
         ---------------                    ----                                -------

<S>                                         <C>                                <C>
         511050                             April 11, 1994                      United States
         (Allowed - Statement of Use due)
</TABLE>


AUDIBLE TONE SEQUENCE
Attorney Docket No. NEO 2-203US

         "A sequence of audible tones of successively increasing frequencies
from minimum to maximum values broadcast to produce a unique sound"

<TABLE>
<CAPTION>
         REG. NO.                           DATE                                COUNTRY
         --------                           ----                                -------

<S>                                         <C>                                <C>
         1,959642                           March 5, 1996                       United States
</TABLE>


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   57
                                                                       EXHIBIT B

                                    WARRANTY


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   58
                                                                     EXHIBIT 2.1

                                TRADEMARK LICENSE

                           TRADEMARK LICENSE AGREEMENT

         THIS AGREEMENT between Neoprobe Corporation, a Delaware corporation
(hereinafter "Neoprobe") and United States Surgical Corporation, a Delaware
corporation (hereinafter "USSC").

         WHEREAS Neoprobe is the sole and exclusive owner of the entire right,
title and interest in and to trademark(s) and trade name(s) (collectively
referred to as "Neoprobe Trademarks") used by Neoprobe in connection with the
promotion and sale of Neoprobe Products (as defined in the License and
Distributorship Agreement executed on even date herewith);

         WHEREAS USSC is desirous of acquiring a **** right and license for the
marketing and promotion of Neoprobe Products in connection with Neoprobe
Trademarks and whereas Neoprobe is willing to grant such license;

         NOW THEREFORE in consideration of the mutual considerations set forth
and other good and valuable consideration, the receipt and sufficiency of which
is acknowledged by each of the parties, it is understood and agreed as follows:

1. GRANT OF THE LICENSE

         1.1 Subject to the terms and conditions hereinafter set forth, Neoprobe
hereby grants to USSC for the term of this Agreement a **** right and license to
use Neoprobe Trademarks in connection with the marketing, promotion and sale of
Neoprobe Products.

         1.2 The license does not include any right to grant sublicenses.

         1.3 This Agreement and the license granted hereunder may not be
assigned without the written consent of Neoprobe.

2. TERM

         2.1. This Agreement shall be effective as of the date it is executed.


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   59
         2.2 The term of this Agreement shall continue for the term of the
License and Distributorship Agreement executed on even date herewith.


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   60
3. QUALITY CONTROL

         Neoprobe licenses USSC to use the Neoprobe Trademarks upon the terms
herein set forth, during the period of this Agreement in advertising,
identifying and selling Neoprobe Products in case, and only in case, such
Neoprobe Products are of approved standards and are not advertised, labeled or
packaged in any manner tending to mislead or deceive the public.

4. PROTECTION OF NEOPROBE TRADEMARKS

         USSC acknowledges Neoprobe's exclusive right, title and interest in and
to the Neoprobe Trademarks and will not, in any way, directly or indirectly, do
or cause to be done any act or thing contesting or in any way impairing or
tending to impair any part of said right, title and interest in connection with
the use of Neoprobe Trademarks. USSC shall not in any manner represent that it
has any ownership in Neoprobe Trademarks or any registration thereof and USSC
acknowledges that use of Neoprobe Trademarks by it shall not create in USSC any
right, title or interest in or to the Neoprobe Trademarks, but all use of
Neoprobe Trademarks shall inure to the benefit of Neoprobe.


         IN WITNESS WHEREOF the parties hereto have executed this Agreement
effective __________


                                            Neoprobe Corporation


ATTEST:_______________                      By:________________________

                                            Title:

                                            Date:



                                            United States Surgical Corporation


ATTEST:_______________                      By:________________________

                                            Title:

                                            Date:


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   61
                                                                     EXHIBIT 3.6

              NEOPROBE PRODUCT PRICING AND NON PRICE TERMS OF SALE

****


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   62
                                                                     EXHIBIT 4.3

                                USSC COMMISSIONS

****


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   63
                                                                    EXHIBIT 10.3

                            SALES PENETRATION LEVELS


                                      ****


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   64
                                                                    EXHIBIT 10.4

                       OWNERSHIP AND CONTROL RESTRICTIONS

Notwithstanding any other provision of this Agreement, USSC hereby covenants and
agrees with Neoprobe that from the effective date of this Agreement until the
second (2nd) anniversary of the termination of this Agreement, unless USSC has
received the prior written consent of Neoprobe granted by its Board of
Directors, USSC will, and will cause each of its Affiliates to:

1.   STANDSTILL AGREEMENT. Not acquire, offer or propose to acquire, nor agree
     to acquire, direct or indirect beneficial ownership (determined under Rule
     13d 3 of the regulations promulgated by the United States Securities and
     Exchange Commission ("SEC") under Section 13(d) of the Securities Exchange
     Act of 1934) of any securities issued by Neoprobe that entitle the holders
     thereof to vote on the election of any directors of Neoprobe, or any
     security convertible into, exchangeable for or exercisable for such
     securities or any option or right to acquire such securities (which
     securities and rights are referred to herein as "Neoprobe Voting
     Securities"), if after such acquisition, the Neoprobe Voting Securities
     then beneficially owned by USSC and its Affiliates, represent (or would
     represent if they were exercised, exchanged, converted or acquired) voting
     power greater than five percent (5%) of any class of then outstanding
     Neoprobe Voting Securities;

2.   NOTICE OF TRANSACTIONS. Compliance. Notify Neoprobe in writing of any plans
     of USSC or its Affiliates to acquire or dispose of beneficial ownership of
     Neoprobe Voting Securities, reasonably in advance of any such action; make
     any such acquisitions or dispositions in compliance with applicable laws
     and regulations, and, as USSC may be deemed to be an insider of Neoprobe
     for purposes of the federal securities laws because of the relationships
     created by this Agreement, make any such acquisitions or dispositions only
     during times when Neoprobe advises USSC that it is not subject to trading
     restrictions because of its insider status;

3.   VOTING. Take such action as may be required so that all Neoprobe Voting
     Securities beneficially owned by USSC or any of its Affiliates are voted
     for each of the nominees to the Board of Directors of Neoprobe who were
     nominated for such election by the Board of Directors or a duly constituted
     committee of the Board of Directors having authority in such matters and so
     that all such Neoprobe Voting Securities are voted on all other matters to
     be voted on by holders of Neoprobe Voting Securities as recommended by the
     Board of Directors of Neoprobe or a duly constituted committee of the Board
     of Directors having authority in such matters or, if such recommendation is


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   65
     not made, in not less than the same proportion as the votes cast by the
     other holders of Neoprobe Voting Securities with respect to such matters;
     and be present, in person or by proxy, at all meetings of stockholders of
     Neoprobe so that all shares of Neoprobe Voting Securities beneficially
     owned by USSC or its Affiliates may be counted for the purposes of
     determining the presence of a quorum at such meetings;

4.   VOTING TRUST. Not deposit any Neoprobe Voting Securities in a voting trust
     or, except as otherwise provided herein, subject any Neoprobe Voting
     Securities to any arrangement or agreement with respect to the voting of
     such Neoprobe Voting Securities;

5.   SOLICITATION OF PROXIES. Not solicit proxies for any Neoprobe Voting
     Securities, nor become a "participant in a solicitation" as such term is
     defined in instruction 3 to item 4 of Schedule 14A to Regulation 14A
     promulgated by the SEC under Section 14(a) of the Securities Exchange Act
     of 1934 (the "Exchange Act") with respect to Neoprobe Voting Securities;
     nor advise, encourage or influence any third party with respect to the
     solicitation of proxies with respect to Neoprobe Voting Securities; nor
     initiate, propose or induce any third party to initiate or propose the
     submission of any matter to a meeting of the stockholders of Neoprobe.

6.   ACTS IN CONCERT WITH OTHERS. Become a member of any partnership, limited
     partnership, syndicate or other group, or otherwise act in concert with any
     third person, for the purpose of acquiring, holding, voting or disposing of
     Neoprobe Voting Securities;

7.   RESTRICTIONS ON TRANSFER OF NEOPROBE VOTING SECURITIES. Neither USSC nor
     any Affiliate shall dispose of beneficial ownership of Neoprobe Voting
     Securities except (i) to a corporation of which USSC owns not less than 80%
     of the voting power entitled to be cast in the election of directors (a
     "Controlled Corporation"), so long as such Controlled Corporation agrees to
     hold such voting Stock subject to all the provisions of this Agreement, and
     agrees to transfer such Neoprobe Voting Securities to USSC or another
     Controlled Corporation if it ceases to be a Controlled Corporation; or (ii)
     in transactions which do not, directly or indirectly, result in any person
     or group owning or having the right to acquire beneficial ownership of
     Neoprobe Voting Securities with aggregate voting power of five percent or
     more of the aggregate voting power of all outstanding Neoprobe Voting
     Securities or (iii) in response to an offer to purchase or exchange for
     cash or other consideration any Neoprobe Voting Securities that is approved
     by the Board of Directors of Neoprobe within the time such Board is
     required,


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   66
     pursuant to regulations under the Exchange Act, to advise Neoprobe
     stockholders of such Board's position on such offer; and

8.   ANNOUNCEMENTS. Not enter into, make any proposal concerning, enter into any
     negotiations concerning, nor make any public announcement about, any
     transaction intended to affect the control of Neoprobe or the ownership of
     any material portion of its assets.

9.   SUSPENSION. The prohibitions on actions by USSC set forth in Sections 1
     through 8 above shall be suspended if (a) Neoprobe makes a public
     announcement to the effect that it has entered into any agreement,
     including an agreement in principal, to engage in an Extraordinary
     Transaction or that it is engaged in substantive negotiations with a third
     party with a view to engaging in an Extraordinary Transaction or if (b) a
     third party files a Schedule 13D or a Schedule 14D(1) with the SEC
     proposing or stating its intention to propose an Extraordinary Transaction
     and Neoprobe does not within the time required by Rule 14(e)(2) reject such
     proposal; but such suspension shall be terminated when Neoprobe or any such
     third party makes a public announcement, or files any Schedule or report
     with the SEC, to the effect that such agreement, negotiations, or offer
     have been terminated without consummation of an Extraordinary Transaction;
     provided, however, that if during any time when the prohibitions of Section
     1 above have been suspended under the first clause of this Section 9, USSC
     acquires any Neoprobe Voting Securities in excess of the percentage set
     forth in Section 1 above, USSC may retain ownership thereof subject to all
     of the provisions of this Agreement and the percentage set forth in Section
     1 above shall be deemed to be amended to include such Neoprobe Voting
     Securities.

10.  "EXTRAORDINARY TRANSACTIONS". means (a) the acquisition by any person
     (defined for the purposes of this definition to mean any person within the
     meaning of Section 13(d) of 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, of the beneficial ownership
     (determined under Rule 13d(3) of the Regulations promulgated by the SEC
     under Section 13(d) of the Exchange Act) of Neoprobe Voting Securities
     having a majority of the voting power of all the Neoprobe Voting Securities
     issued by Neoprobe in the election of directors at the next meeting of the
     holders of Neoprobe Voting Securities to be held for such purpose; (b) a
     merger or consolidation of Neoprobe with another person, other than a
     merger or consolidation in which the holders of Neoprobe Voting Securities
     issued and outstanding immediately before such merger or consolidation
     continue to hold Neoprobe Voting Securities in the surviving or resulting
     corporation (in the same relative proportions to each other as existed
     before


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   67
     such event) comprising 80% or more of the voting power for all purposes of
     the surviving or resulting corporation; or (d) the transfer of
     substantially all of the assets of Neoprobe to another person other than a
     transfer to a transferee, 80% or more of the voting power of which is owned
     or controlled by Neoprobe or by the holders of Neoprobe Voting Securities
     issued and outstanding immediately before such transfer in the same
     relative proportions to each other as existed before such event


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   68
                                                                    EXHIBIT 14.2

                      MATERIAL INTELLECTUAL PROPERTY RIGHTS

         "Technology Transfer Agreement" between The Dow Chemical Company and
Neoprobe Corporation, effective July 29, 1992.

         "Patent License Agreement -- Exclusive" between The Dow Chemical
Company and the National Institutes of Health, the Centers for Disease Control
and/or the Alcohol, Drug Abuse and Mental Health Administration, effective as of
January 1993.

         "Research and Development Agreement" between Neoprobe Corporation, Ohio
State University, and Director of Development of the State of Ohio, Acting on
Behalf of the State of Ohio, dated as of July 23, 1985.

         "The Ohio State University Research Foundation Task Order Agreement for
Sponsored Clinical Research" between The Ohio State University Research
Foundation and Neoprobe Corporation, executed by the parties on May 15, 1992.

         "License Agreement" between Neoprobe Corporation and The Ohio State
University Research Foundation, dated July 23, 1992.

         "License Agreement; Surgery Products License" between Biomeasure, Inc.
and Neoprobe Corporation, dated August 1, 1994.

         "License Agreement; Imaging Products License" between Biomeasure, Inc.
and Neoprobe Corporation, dated August 1, 1994.

         "Research and Development Agreement" and "Sublicense Agreement" between
XTL Biopharmaceuticals, Ltd. and Neoprobe Corporation, both of which are dated
February 13, 1996.

         "Cooperative Research and Development Agreement" directed to "The Use
of Monoclonal Antibodies and Development of Novel Recombinant Immunoglobuling
Forms for Radioimmunoguided Surgery of Cancer" between the National Cancer
Institute (Jeffrey Schlom, Ph.D., Principal Investigator) and Neoprobe
Corporation (William A. Eisenhardt, Ph.D., Principal Investigator), executed on
behalf of the National Cancer Institute on June 9, 1995 and on behalf of
Neoprobe Corporation on August 7, 1995.

         "License Agreement" between Neoprobe Corporation and The Ohio State
University Research Foundation (U.S. Patent No. 5,383,456), dated August 15,
1995.


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.
<PAGE>   69
                             EXHIBIT 14.2 CONTINUED

         "License Agreement" between Neoprobe Corporation and The Ohio State
University Research Foundation (U.S. Patent Application No. 08/227,447), dated
August 15, 1995.


         "License Agreement" between Cancer Research Campaign Technology Limited
and Neoprobe Corporation dated November 1, 1989.

         "Disclosure and License Agreement for Biotechnology-Derived Therapeutic
Products" between The New York Blood Center, Inc. and Neoprobe Corporation dated
August 12, 1992.

         "License Agreement" between the National Technical Information Service,
a primary unit of the United States Department of Commerce, and Neoprobe
Corporation, executed on behalf of Neoprobe Corporation on January 7, 1987.

         ****


Omitted portions of this Exhibit 10.4.20 have been filed separately with the
Commission and are subject to a request for confidential treatment under Rule
24b-2

**** Omitted and filed separately under Rule 24b-2 pursuant to which Neoprobe
Corporation has requested Confidential Treatment of this information.


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