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                                                                     Exhibit 4.4

                   AMENDMENT NUMBER 1 TO THE RIGHTS AGREEMENT

       This Amendment Number 1 ("Amendment") to the Rights Agreement
("Agreement") between Neoprobe Corporation, a Delaware corporation ("Company"),
and Continental Stock Transfer & Trust Company ("Rights Agent") is dated as of
February 16, 1999.

       WHEREAS, the Company and the Rights Agent entered into the Agreement on
July 18, 1995 in connection with a rights dividend declared by the board of
directors of the Company; and

       WHEREAS, the Company and the Rights Agent desire to amend the Agreement
in order to provide for the sale and issuance of a new series of convertible
preferred stock of the Company and warrants to purchase common stock of the
Company, par value $.001, in order to raise funds for the Company.

       NOW THEREFORE, the Company and the Rights Agent hereby agree to amend
the Agreement as follows:

       1.     The definition of "Acquiring Person" contained in Section 1.(a)
of the Agreement is hereby deleted in its entirety and the following language
be inserted in lieu thereof:

              "Acquiring Person" shall mean any Person who or which, together
              with all Affiliates and Associates of such Person, shall be the
              Beneficial Owner of 15% or more of the Common Stock then
              outstanding, but shall not include (i) the Company, (ii) any
              Subsidiary of the Company, (iii) any employee benefit plan of the
              Company or of any Subsidiary of the Company, (iv) any Person
              organized, appointed or established by the Company for or
              pursuant to the terms of any such plan, or (v) any Person who
              becomes a Beneficial Owner of 15% or more of the Common Stock
              then outstanding solely because such Person or its affiliates and
              associates (1) acquired shares of 5% Series B Convertible
              Preferred Stock, par value $.001 per share, stated value $100 per
              share ("Series B Preferred Stock"), of the Company from the
              Company, (2) acquired Class L Warrants of the Company ("Class L
              Warrants") from the Company (3) acquired options ("Advisory
              Options") to purchase shares of Series B Preferred Stock and
              Class L Warrants from the Company pursuant to the Financial
              Advisory Agreement between the Company and Paramount Capital,
              Inc. dated February 16, 1999, (4) acquired Common Stock through
              the conversion of Series B Convertible Preferred Stock, which
              such Person purchased directly from the Company, through the
              exercise of Class L Warrants or Advisory Warrants, which such
              Person obtained directly from the Company, through a Common Stock
              dividend on shares of Series B Preferred Stock declared by the
              Company or any other issuance of Common Stock in respect of the
              Series B Preferred Stock or Class L Warrants (including the
              shares of Series B Preferred Stock and Class L Warrants
              underlying the Advisory Options), pursuant to the terms of the
              Certificate of Designations of 5% Series B Preferred Convertible
              Preferred Stock of Neoprobe Corporation ("Certificate of
              Designations"), pursuant to any provision of the Class L Warrants
              or pursuant to any provision of the Preferred Stock and Warrant
              Purchase Agreement ("Purchase Agreement") dated February 16, 1999
              by and among the Company, The Aries Master Fund, a Cayman Island
              Exempted Company ("Master Fund"), and The Aries Domestic Fund,
              L.P. ("Domestic Fund"), and the agreements referred to therein,
              or (5) is the Master Fund or the Domestic Fund or their
              respective affiliates or associates unless such entities acquire
              more than an aggregate of 1,000,000 shares of Common Stock (such
              number to be adjusted to reflect the effect of stock splits,
              stock dividends and similar events affecting Common Stock after
              the date of Amendment No. 1 to this Rights Agreement) in addition
              to acquisitions otherwise described in clauses (v)(1), (v)(2),
              (v)(3) and (v)(4) of this paragraph.





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       2.     The definition of "Section 11(a)(ii) Event" contained in Section
1.(a) of the Agreement is hereby deleted in its entirety and the following
language be inserted in lieu thereof:

       "Section 11(a)(ii) Event" shall have the meaning set forth in Section
11(a)(ii) hereof.

       Section 11(a)(ii) of the Agreement is hereby deleted in its entirety and
the following language be inserted in lieu thereof:
              Section 11. (a)(ii) If any Person (other than the Company, any
              Subsidiary of the Company, any employee benefit plan of the
              Company or of any Subsidiary of the Company, or any Person or
              entity organized, appointed or established by the Company for or
              pursuant to the terms of any such plan), alone or together with
              its Affiliates and Associates at any time after the Rights
              Dividend Declaration Date, becomes a Beneficial Owner of 15% or
              more of the Common Stock then outstanding, a "Section 11(a)(ii)
              Event" shall be deemed to have occurred; unless the event causing
              the 15% threshold to be crossed

                     (1)    is a Section 13 Event;

                     (2)    is an acquisition of Common Stock pursuant to a
                     tender offer or an exchange offer for all outstanding
                     Common Stock at a price and on terms determined by at
                     least a majority of the members of the Board of Directors
                     who are not officers of the Company and who are not
                     representatives, nominees, Affiliates or Associates of an
                     Acquiring Person, after receiving advice from one or more
                     investment banking firms, to be (A) at a price which is
                     fair to stockholders (taking into account all factors
                     which such members of the Board deem relevant including,
                     without limitation, prices which could reasonably be
                     achieved if the Company or its assets were sold on an
                     orderly basis designed to realize maximum value) and (B)
                     otherwise in the best interests of the Company and its
                     stockholders;

                     (3)    (i) is the acquisition of Series B Preferred Stock
                     and Series B Preferred Stock Warrants from the Company,
                     (ii) is the conversion of Series B Preferred Stock into
                     Common Stock by a Person who purchased the shares of
                     Series B Preferred Stock directly from the Company, (iii)
                     is the purchase of Common Stock by the exercise of Class L
                     Warrants, which were obtained by the Persons exercising
                     them directly from the Company, (iv) is the acquisition of
                     Common Stock by conversion of Series B Preferred Stock and
                     exercise of Class L Warrants issuable upon exercise of the
                     Advisory Options, (v) is the acquisition of Common Stock
                     pursuant to any provision of the Purchase Agreement and
                     the agreements referred to therein, (vi) is the
                     acquisition of Common Stock through a Common Stock
                     dividend on shares of Series B Preferred Stock declared by
                     the Company or any other issuance of Common Stock in
                     respect of the Series B Preferred Stock or the Series B
                     Preferred Stock Warrants pursuant to the terms of the
                     Certificate of Designations, or (vii) the acquisition of
                     up to an aggregate of 1,000,000 shares of Common Stock,
                     such number to be adjusted to reflect stock splits, stock
                     dividends and similar events affecting Common Stock
                     occurring after the date of Amendment No. 1 to this Rights
                     Agreement, by the Master Fund or the Domestic Fund or any
                     of their respective affiliates and associates in addition
                     to acquisitions described in clauses (i), (ii), (iii),
                     (iv),  (v) and (vi) of this Section 11(a)(ii)(3).

              Promptly following the first occurrence of any Section 11(a)(ii)
              Event, proper provision shall be made so that each holder of a
              Right (except as provided below and in Section 7(e) hereof) shall
              thereafter have the right to receive, upon exercise thereof at
              the then current Purchase Price in accordance with the terms of
              this Agreement, in lieu of Preferred Stock or fractions thereof,
              such number of shares of Common Stock of the Company as shall
              equal the result obtained by (I) multiplying the then current
              Purchase Price by the then number of shares of Preferred Stock or
              fractions thereof for which a Right was exercisable immediately
              prior to the first occurrence of a Section 11(a)(ii) Event, and
              (II) dividing that product (which, following such first
              occurrence, shall thereafter be referred to as





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              the "Purchase Price" for each Right and for all purposes of this
              Agreement) by 50% of the current market price (determined
              pursuant to Section 11(d) hereof) per shares of Common Stock on
              the date of such first occurrence (such number of shares, the
              "Adjustment Stock").

       3.     Except as specifically amended by this Amendment, the provisions
of the Agreement remain in full force and effect.

       IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the day and year first written above.


                                   NEOPROBE CORPORATION




                                   By: /s/ David C. Bupp                        
                                      ------------------------------------------
                                      David C. Bupp, Chief Executive Officer





                                   CONTINENTAL STOCK TRANSFER & TRUST COMPANY


                                   By: /s/ William F. Seegraber                 
                                      ------------------------------------------

                                   Print Name: William F. Seegraber             
                                              ----------------------------------
                                   Print Title:    Vice President               
                                               ---------------------------------





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