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                                                                     EXHIBIT 4.3


                          REGISTRATION RIGHTS AGREEMENT

        This REGISTRATION RIGHTS AGREEMENT (this "AGREEMENT"), dated as of
December 14, 2001, is entered into by and among EntreMed, Inc., a Delaware
corporation, with headquarters located at 9640 Medical Center Drive, Rockville,
Maryland 20850 (the "COMPANY"), and the undersigned buyers (each, a "BUYER" and
collectively, the "BUYERS").

        WHEREAS:

        A.      Pursuant to a Securities Purchase Agreement, dated the date
                hereof (the "SECURITIES PURCHASE AGREEMENT"), among the Company
                and the Buyers, the Company has agreed to sell and the Buyers
                have agreed to purchase units of securities of the Company (the
                "UNITS") consisting of (i) the Company's Common Stock, par value
                $.01 per share (the "COMMON SHARES"), and (ii) Warrants (the
                "WARRANTS") to purchase shares of Common Stock (the "WARRANT
                SHARES"); and

        B.      To induce the Buyers to execute and deliver the Securities
                Purchase Agreement, the Company has agreed to provide certain
                registration rights under the Securities Act of 1933, as
                amended, and the rules and regulations thereunder, or any
                similar successor statute (collectively, the "1933 ACT").

        NOW, THEREFORE, in consideration of the premises and the mutual
covenants contained herein and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the Company and the
Buyers hereby agree as follows:

                1.      DEFINITIONS

        As used in this Agreement, the following terms shall have the following
meanings:

                        a.      "INVESTOR" means a Buyer, any transferee or
                                assignee thereof to whom a Buyer assigns its
                                rights under this Agreement and who agrees to
                                become bound by the provisions of this Agreement
                                in accordance with Section 10 and any transferee
                                or assignee thereof to whom a transferee or
                                assignee assigns its rights under this Agreement
                                and who agrees to become bound by the provisions
                                of this Agreement in accordance with Section 10.

                        b.      "MATERIALLY DETRIMENTAL" means, in the good
                                faith judgment of the Board of Directors of the
                                Company as set forth in a certificate signed by
                                the Chief Executive Officer, Vice
                                President-Finance or General Counsel of the
                                Company, the filing in question would be
                                materially


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                                detrimental to the Company by reason of (i) any
                                proceeding before, or material event involving,
                                the Food and Drug Administration, or (ii) any
                                proposal or plan of the Company or any of its
                                Subsidiaries to engage in any sale, acquisition,
                                merger, consolidation, reorganization, tender
                                offer or similar transaction.

                        c.      "PERSON" means a corporation, a limited
                                liability company, an association, a
                                partnership, an organization, a business, an
                                individual, a governmental or political
                                subdivision thereof or a governmental agency or
                                any other entity.

                        d.      "REGISTER," "REGISTERED," and "REGISTRATION"
                                refer to a registration effected by preparing
                                and filing one or more Registration Statements
                                (defined below) in compliance with the 1933 Act
                                and pursuant to Rule 415 under the 1933 Act or
                                any successor rule providing for offering
                                securities on a continuous basis ("RULE 415"),
                                and the declaration or ordering of effectiveness
                                of such Registration Statement(s) by the United
                                States Securities and Exchange Commission (the
                                "SEC").

                        e.      "REGISTRABLE SECURITIES" means (i) the Common
                                Shares purchased by the Buyers pursuant to the
                                Securities Purchase Agreement, (ii) the Warrant
                                Shares issued or issuable upon exercise of the
                                Warrants and (iii) any shares of capital stock
                                issued or issuable with respect to such Common
                                Shares, Warrants or Warrant Shares as a result
                                of any stock split, stock dividend,
                                recapitalization, exchange or similar event or
                                otherwise, without regard to any limitation on
                                the exercise of the Warrants.

                        f.      "REGISTRATION STATEMENT" means a registration
                                statement of the Company filed under the 1933
                                Act and pursuant to Rule 415.

Capitalized terms used herein and not otherwise defined herein shall have the
respective meanings set forth in the Securities Purchase Agreement.

                2.      REGISTRATION

                        a.      Shelf Registration. The Company shall prepare,
                                and, as soon as practicable, but in no event
                                later than thirty (30) calendar days after the
                                Closing Date (the "FILING DATE"), file with the
                                SEC a Registration Statement or Registration
                                Statements (as is necessary), containing the
                                Plan of Distribution set forth hereto as Exhibit
                                B, on Form S-3 (or



                                       2
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                                if such form is unavailable, such other form as
                                is available for registration) covering the
                                resale of all of the Registrable Securities. The
                                Company shall use its reasonable best efforts to
                                have the Registration Statement declared
                                effective by the SEC as soon as practicable, but
                                in no event later than the earlier of (i) five
                                (5) business days after the Company is advised
                                orally or in writing by the SEC that the SEC
                                will not review or has no further comments
                                concerning the Registration Statement and (ii)
                                the ninetieth (90th) calendar day after the
                                Closing Date (the "EFFECTIVENESS DATE").

                        b.      Piggy-Back Registrations. If at any time prior
                                to the expiration of the Registration Period (as
                                defined in Section 3(a)) the Registrable
                                Securities are not already covered by an
                                effective Registration Statement and the Company
                                proposes to file with the SEC a Registration
                                Statement relating to an offering for its own
                                account or the account of others under the 1933
                                Act of any of its securities (other than on Form
                                S-4 or Form S-8 (or their equivalents at such
                                time) relating to securities to be issued solely
                                in connection with any sale, acquisition,
                                merger, consolidation, reorganization or similar
                                transaction of any entity or business or equity
                                securities issuable in connection with stock
                                option or other employee benefit plans) the
                                Company shall promptly send to each Investor
                                written notice of the Company's intention to
                                file a Registration Statement and of such
                                Investor's rights under this Section 2(b) and,
                                if within twenty (20) days after receipt of such
                                notice, such Investor shall so request in
                                writing, the Company shall include in such
                                Registration Statement all or any part of the
                                Registrable Securities such Investor requests to
                                be registered, subject to the priorities set
                                forth in Section 2(b) below. No right to
                                registration of Registrable Securities under
                                this Section 2(b) shall be construed to limit
                                any registration required under Section 2(a).
                                The obligations of the Company under this
                                Section 2(b) may be waived by the Buyers. If an
                                offering in connection with which an Investor is
                                entitled to registration under this Section 2(b)
                                is an underwritten offering, then each Investor
                                whose Registrable Securities are included in
                                such Registration Statement shall, unless
                                otherwise agreed by the Company, offer and sell
                                such Registrable Securities in an underwritten
                                offering using the same underwriter or
                                underwriters and, subject to the provisions of
                                this Agreement, on the same terms and conditions
                                as other shares of Common Stock included in such
                                underwritten offering. If a registration



                                       3
<PAGE>

                                pursuant to this Section 2(b) is to be an
                                underwritten public offering and the managing
                                underwriter(s) advise the Company in writing,
                                that in their reasonable good faith opinion,
                                marketing or other factors dictate that a
                                limitation on the number of shares of Common
                                Stock which may be included in the Registration
                                Statement is necessary to facilitate and not
                                adversely affect the proposed offering, then the
                                Company shall include in such registration: (1)
                                first, all securities the Company proposes to
                                sell for its own account, (2) second, up to the
                                full number of securities proposed to be
                                registered for the account of the holders of
                                securities entitled to inclusion of their
                                securities in the Registration Statement by
                                reason of demand registration rights, and (3)
                                third, the securities requested to be registered
                                by the Investors and other holders of securities
                                entitled to participate in the registration, as
                                of the date hereof, drawn from them pro rata
                                based on the number each has requested to be
                                included in such registration.

                        c.      Allocation of Registrable Securities. The
                                initial number of Registrable Securities
                                included in any "piggyback" Registration
                                Statement under Section 2(b) and each increase
                                in the number of Registrable Securities included
                                therein shall be allocated pro rata among the
                                Investors based on the number of Registrable
                                Securities held, or which could be held, by each
                                Investor at the time the Registration Statement
                                covering such initial number of Registrable
                                Securities or increase thereof is declared
                                effective by the SEC.

                        d.      Legal Counsel. The Investors shall have the
                                right to select one (1) legal counsel to review
                                and oversee at the Buyers' expense any offering
                                pursuant to this Section 2 ("LEGAL COUNSEL"),
                                which shall be Robinson Silverman Pearce
                                Aronsohn & Berman LLP or such other counsel as
                                hereafter designated by the holders of a
                                majority of Registrable Securities. The Company
                                shall reasonably cooperate with Legal Counsel in
                                performing the Company's obligations under this
                                Agreement.

                        e.      Ineligibility for Form S-3. In the event that
                                Form S-3 is not available for any registration
                                of Registrable Securities hereunder, the Company
                                shall (i) register the sale of the Registrable
                                Securities on another appropriate form, if any,
                                and (ii) undertake to register the Registrable
                                Securities on Form S-3 as soon as such form is
                                available, provided that the Company shall
                                maintain the effectiveness of the



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<PAGE>

                                Registration Statement then in effect until such
                                time as a Registration Statement on Form S-3
                                covering the Registrable Securities has been
                                declared effective by the SEC.

                        f.      Rule 416. The Company and the Investors each
                                acknowledge that each Registration Statement
                                prepared in accordance hereunder shall include
                                an indeterminate number of Registrable
                                Securities pursuant to Rule 416 under the 1933
                                Act so as to cover any and all Registrable
                                Securities which may become issuable to prevent
                                dilution resulting from stock splits, stock
                                dividends or similar transactions in accordance
                                with the provisions contained in the Warrants
                                (collectively, the "RULE 416 SECURITIES"). In
                                this regard, the Company agrees to use
                                reasonable efforts to ensure that the maximum
                                number of Registrable Securities which may be
                                registered pursuant to Rule 416 under the 1933
                                Act are covered by each Registration Statement.

                        g.      Sufficient Number of Shares Registered. In the
                                event the number of shares available under a
                                Registration Statement filed pursuant to Section
                                2(a) is insufficient to cover all of the
                                Registrable Securities (a "DEFICIT FAILURE"),
                                the Company shall amend the Registration
                                Statement, or file a new Registration Statement
                                (on the short form available therefor, if
                                applicable), or both, so as to cover at least
                                one hundred percent (100%) of such Registrable
                                Securities in each case, as soon as practicable,
                                but in any event not later than fifteen (15)
                                days after the necessity therefor arises. The
                                Company shall use its reasonable best efforts to
                                cause such amendment and/or new Registration
                                Statement to become effective as soon as
                                practicable following the filing thereof. For
                                purposes of the foregoing provision, the number
                                of shares available under a Registration
                                Statement shall be deemed "insufficient to cover
                                all of the Registrable Securities" if at any
                                time the number of Registrable Securities is
                                greater than the number of shares of Common
                                Stock available for resale under such
                                Registration Statement. For purposes of the
                                calculation set forth in the foregoing sentence,
                                any restrictions on the exercisability of the
                                Warrants shall be disregarded and such
                                calculation shall assume that the Warrants are
                                then exercisable into shares of Company Common
                                Stock.

                3.      RELATED OBLIGATIONS



                                       5
<PAGE>

        Whenever an Investor has requested that any Registrable Securities be
registered pursuant to Section 2(b) or at such time as the Company is obligated
to file a Registration Statement with the SEC pursuant to Section 2(a) or 2(g),
the Company will use its reasonable best efforts to effect the registration of
the Registrable Securities in accordance with the intended method of disposition
thereof and, pursuant thereto, the Company shall have the following obligations:

                        a.      Registration. The Company shall promptly prepare
                                and file with the SEC a Registration Statement
                                with respect to the Registrable Securities as
                                provided in Section 2(a), and shall keep such
                                Registration Statement effective pursuant to
                                Rule 415 at all times until the earlier of (i)
                                the date on which the Investors shall have sold
                                all the Registrable Securities or (ii) the date
                                on which all Registrable Securities may be sold
                                without volume restrictions pursuant to Rule
                                144(k) promulgated under the 1933 Act (the
                                "REGISTRATION PERIOD"), which Registration
                                Statement (including any amendments or
                                supplements thereto and prospectuses contained
                                therein) shall not contain any untrue statement
                                of a material fact or omit to state a material
                                fact required to be stated therein, or necessary
                                to make the statements therein, in light of the
                                circumstances in which they were made, not
                                misleading.

                        b.      Amendments. The Company shall prepare and file
                                with the SEC such amendments (including
                                post-effective amendments) and supplements to a
                                Registration Statement and the prospectus used
                                in connection with such Registration Statement,
                                which prospectus is to be filed pursuant to Rule
                                424 promulgated under the 1933 Act, as may be
                                necessary to keep such Registration Statement
                                effective at all times during the Registration
                                Period, and, during such period, comply with the
                                provisions of the 1933 Act with respect to the
                                disposition of all Registrable Securities of the
                                Company covered by such Registration Statement
                                until such time as all of such Registrable
                                Securities shall have been disposed of in
                                accordance with the intended methods of
                                disposition by the seller or sellers thereof as
                                set forth in such Registration Statement.

                        c.      Legal Counsel Review. The Company shall permit
                                Legal Counsel to review and comment upon a
                                Registration Statement and all amendments and
                                supplements thereto at least seven (7) days
                                prior to their filing with the SEC, and not file
                                any document in a form to which Legal Counsel
                                reasonably objects. The Company shall not submit
                                a request for acceleration of the effectiveness
                                of a



                                       6
<PAGE>

                                Registration Statement or any amendment or
                                supplement thereto without the prior approval of
                                Legal Counsel, which approval shall not be
                                unreasonably withheld. The Company shall furnish
                                to Legal Counsel, without charge, (i) any
                                correspondence from the SEC or the staff of the
                                SEC to the Company or its representatives
                                relating to any Registration Statement, (ii)
                                promptly after the same is prepared and filed
                                with the SEC, one (1) copy of any Registration
                                Statement and any amendment(s) thereto,
                                including financial statements and schedules,
                                all documents incorporated therein by reference
                                and all exhibits and (iii) upon the
                                effectiveness of any Registration Statement, one
                                (1) copy of the prospectus included in such
                                Registration Statement and all amendments and
                                supplements thereto.

                        d.      Disclosure Materials. The Company shall furnish
                                to each Investor whose Registrable Securities
                                are included in any Registration Statement,
                                without charge, (i) promptly after the same is
                                prepared and filed with the SEC, at least one
                                (1) copy of such Registration Statement and any
                                amendment(s) thereto, including financial
                                statements and schedules, all documents
                                incorporated therein by reference and all
                                exhibits, (ii) upon the effectiveness of any
                                Registration Statement, ten (10) copies of the
                                prospectus included in such Registration
                                Statement and all amendments and supplements
                                thereto (or such other number of copies as such
                                Investor may reasonably request) and (iii) such
                                other documents, including copies of any
                                preliminary or final prospectus, as such
                                Investor may reasonably request from time to
                                time in order to facilitate the disposition of
                                the Registrable Securities owned by such
                                Investor.

                        e.      State Securities Laws. If state securities law
                                registration or qualification is required, the
                                Company shall use reasonable efforts to (i)
                                register and qualify the Registrable Securities
                                covered by a Registration Statement under such
                                state securities or "blue sky" laws of such
                                jurisdictions in the United States as Legal
                                Counsel or any Investor reasonably requests,
                                (ii) prepare and file in those jurisdictions,
                                such amendments (including post-effective
                                amendments) and supplements to such
                                registrations and qualifications as may be
                                necessary to maintain the effectiveness thereof
                                during the Registration Period, (iii) take such
                                other actions as may be necessary to maintain
                                such registrations and qualifications in effect
                                at all times during the Registration Period, and
                                (iv) take all other actions reasonably necessary



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<PAGE>

                                or advisable to qualify the Registrable
                                Securities for sale in such jurisdictions;
                                provided, however, that the Company shall not be
                                required in connection therewith or as a
                                condition thereto to (x) qualify to do business
                                in any jurisdiction where it would not otherwise
                                be required to qualify but for this Section
                                3(e), (y) subject itself to general taxation in
                                any such jurisdiction, or (z) file a general
                                consent to service of process in any such
                                jurisdiction. The Company shall promptly notify
                                Legal Counsel and each Investor who holds
                                Registrable Securities of the receipt by the
                                Company of any notification with respect to the
                                suspension of the registration or qualification
                                of any of the Registrable Securities for sale
                                under the securities or "blue sky" laws of any
                                jurisdiction in the United States or its receipt
                                of actual notice of the initiation or
                                threatening of any proceeding for such purpose.

                        f.      Underwriting Agreement. In the event the
                                Investors who hold a majority of the Registered
                                Securities being offered in an offering are
                                entitled to select underwriters for such
                                offering, the Company agrees to enter into and
                                to perform its obligations under an underwriting
                                agreement, in usual and customary form,
                                including, without limitation, customary
                                indemnification and contribution obligations,
                                with the underwriters of such offering.

                        g.      Notification. As promptly as practicable after
                                becoming aware of such event, the Company shall
                                notify Legal Counsel and each Investor in
                                writing of the happening of any event as a
                                result of which the prospectus included in a
                                Registration Statement, as then in effect,
                                includes an untrue statement of a material fact
                                or omission to state a material fact required to
                                be stated therein or necessary to make the
                                statements therein, in light of the
                                circumstances under which they were made, not
                                misleading, and promptly prepare a supplement or
                                amendment to such Registration Statement to
                                correct such untrue statement or omission, and
                                deliver ten (10) copies of such supplement or
                                amendment to Legal Counsel and each Investor (or
                                such other number of copies as Legal Counsel or
                                such Investor may reasonably request). The
                                Company shall also promptly notify Legal Counsel
                                and each Investor in writing (i) when a
                                prospectus or any prospectus supplement or
                                post-effective amendment has been filed, and
                                when a Registration Statement or any
                                post-effective amendment has become effective
                                (notification of such effectiveness shall be
                                delivered to Legal Counsel within one (1) day of
                                such



                                       8
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                                effectiveness by facsimile or by overnight
                                mail), (ii) of any request by the SEC for
                                amendments or supplements to a Registration
                                Statement or related prospectus or related
                                information, and (iii) of the Company's
                                reasonable determination that a post-effective
                                amendment to a Registration Statement would be
                                appropriate.

                        h.      Stop-Order and Suspension. The Company shall use
                                its reasonable best efforts to prevent the
                                issuance of any stop order or other suspension
                                of effectiveness of a Registration Statement, or
                                the suspension of the qualification of any of
                                the Registrable Securities for sale in any
                                jurisdiction and, if such an order or suspension
                                is issued, to obtain the withdrawal of such
                                order or suspension at the earliest possible
                                moment and to notify Legal Counsel and each
                                Investor who holds Registrable Securities being
                                sold (and, in the event of an underwritten
                                offering, the managing underwriters) of the
                                issuance of such order and the resolution
                                thereof or its receipt of actual notice of the
                                initiation or threat of any proceeding for such
                                purpose.

                        i.      Confidential Information. The Company shall hold
                                in confidence and not make any disclosure of
                                information concerning an Investor provided to
                                the Company unless (i) disclosure of such
                                information is necessary to comply with federal
                                or state securities laws, (ii) the disclosure of
                                such information is necessary to avoid or
                                correct a misstatement or omission in any
                                Registration Statement, (iii) the release of
                                such information is ordered pursuant to a
                                subpoena or other final, non-appealable order
                                from a court or governmental body of competent
                                jurisdiction, or (iv) such information has been
                                made generally available to the public other
                                than by disclosure in violation of this
                                Agreement or any other agreement. The Company
                                agrees that it shall, upon learning that
                                disclosure of such information concerning an
                                Investor is sought in or by a court or
                                governmental body of competent jurisdiction or
                                through other means, give prompt written notice
                                to such Investor and allow such Investor, at the
                                Investor's expense, to undertake appropriate
                                action to prevent disclosure of, or to obtain a
                                protective order for, such information.

                        j.      Listing. The Company shall use its reasonable
                                best efforts either to (i) cause all the
                                Registrable Securities covered by a Registration
                                Statement to be listed on each securities
                                exchange on which securities of the same class
                                or series issued by the Company are then listed,
                                if any, if the listing



                                       9
<PAGE>

                                of such Registrable Securities is then permitted
                                under the rules of such exchange, or (ii) secure
                                designation and quotation of all the Registrable
                                Securities covered by the Registration Statement
                                on The Nasdaq National Market System or, if,
                                despite the Company's best efforts to satisfy
                                the preceding clause (i) or (ii), the Company is
                                unsuccessful in satisfying the preceding clause
                                (i) or (ii), to secure the inclusion for
                                quotation on The Nasdaq SmallCap Market for such
                                Registrable Securities and, without limiting the
                                generality of the foregoing, to arrange for at
                                least two (2) market makers to register with the
                                National Association of Securities Dealers, Inc.
                                ("NASD") as such with respect to such
                                Registrable Securities. The Company shall pay
                                all fees and expenses in connection with
                                satisfying its obligation under this Section
                                3(j).

                        k.      Certificates. The Company shall cooperate with
                                the Investors who hold Registrable Securities
                                being offered to facilitate the timely
                                preparation and delivery of certificates (not
                                bearing any restrictive legend) representing the
                                Registrable Securities to be offered pursuant to
                                a Registration Statement and enable such
                                certificates to be in such denominations or
                                amounts, as the case may be, as the Investors
                                may reasonably request and registered in such
                                names as the Investors may request.

                        l.      Transfer Agent. The Company shall provide a
                                transfer agent and registrar, which may be the
                                same Person, of all such Registrable Securities
                                not later than the effective date of such
                                Registration Statement.

                        m.      Reasonable Best Efforts. The Company shall use
                                its reasonable best efforts to cause the
                                Registrable Securities covered by the applicable
                                Registration Statement to be registered with or
                                approved by such other governmental agencies or
                                authorities as may be necessary to consummate
                                the disposition of such Registrable Securities.

                        n.      Compliance with Securities Laws. The Company
                                shall otherwise use its reasonable best efforts
                                to comply with all applicable rules and
                                regulations of the SEC in connection with any
                                registration hereunder and the Company shall use
                                its reasonable best efforts to file with the SEC
                                in a timely manner all reports and documents
                                required of the Company under the 1933 Act and
                                the Securities Exchange Act of 1934, as amended
                                (the "1934 ACT").



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<PAGE>

                        o.      Confirmation. In addition to any notice required
                                to be delivered to Legal Counsel and to the
                                Investors pursuant to Section 3(g), within three
                                (3) business days after the Registration
                                Statement which includes the Registrable
                                Securities is ordered effective by the SEC, the
                                Company shall cause legal counsel for the
                                Company to deliver to the transfer agent for
                                such Registrable Securities confirmation,
                                substantially in the form set forth as Exhibit
                                A, that the Registration Statement has been
                                declared effective by the SEC.

                        p.      Disposition. The Company shall take all other
                                reasonable actions necessary to expedite and
                                facilitate disposition by the Investors of
                                Registrable Securities pursuant to a
                                Registration Statement.

                        q.      Limitation on Registration Statement.
                                Notwithstanding anything to the contrary
                                contained in this Agreement, the Registration
                                Statement required to be filed pursuant to
                                Section 2(a) shall register only the Registrable
                                Securities.

                4.      OBLIGATIONS OF THE INVESTORS

                        a.      At least seven (7) days prior to the first
                                anticipated filing date of the Registration
                                Statement, the Company shall notify each
                                Investor in writing of the information the
                                Company requires from each such Investor if such
                                Investor elects to have any of such Investor's
                                Registrable Securities included in such
                                Registration Statement. It shall be a condition
                                precedent to the obligations of the Company to
                                complete the registration pursuant to this
                                Agreement with respect to the Registrable
                                Securities of a particular Investor that such
                                Investor shall furnish to the Company such
                                information regarding itself and the Registrable
                                Securities held by it as shall be reasonably
                                required to effect the registration of such
                                Registrable Securities and shall execute such
                                documents in connection with such registration
                                as the Company may reasonably request.

                        b.      Each Investor by such Investor's acceptance of
                                the Registrable Securities agrees to cooperate
                                with the Company as reasonably requested by the
                                Company in connection with the preparation and
                                filing of any Registration Statement hereunder,
                                unless such Investor has notified the Company in
                                writing of such Investor's election to exclude
                                all of such Investor's Registrable Securities
                                from such Registration Statement.



                                       11
<PAGE>

                        c.      In the event any Investor elects to participate
                                in an underwritten public offering pursuant to
                                Section 2, each such Investor agrees to enter
                                into and to perform such Investor's obligations
                                under an underwriting agreement, in usual and
                                customary form, including, without limitation,
                                customary indemnification and contribution
                                obligations, with the managing underwriter of
                                such offering and take such other actions as are
                                reasonably required in order to expedite or
                                facilitate the disposition of the Registrable
                                Securities.

                5.      EXPENSES OF REGISTRATION

        All reasonable expenses, other than underwriting discounts and
commissions, incurred in connection with registrations, filings or
qualifications pursuant to Sections 2 and 3, including, without limitation, all
registration, listing and qualifications fees, printers and accounting fees, and
fees and disbursements of counsel for the Company shall be paid by the Company
and, in the event the Company fails to comply with the reasonable requests of
Legal Counsel made pursuant to Section 3(c) of this Agreement, the fees and
disbursements of Legal Counsel, shall be paid by the Company.

                6.      INDEMNIFICATION

        In the event any Registrable Securities are included in a Registration
Statement under this Agreement:

                        a.      To the fullest extent permitted by law, the
                                Company will, and hereby does, indemnify, hold
                                harmless and defend (i) each Investor who holds
                                such Registrable Securities, and (ii) the
                                directors, officers, partners, employees,
                                agents, representatives of, and each Person, if
                                any, who controls any Investor within the
                                meaning of the 1933 Act or 1934 Act, and any
                                underwriter (as defined in the 1933 Act) for the
                                Investors, and the directors and officers of,
                                and each Person, if any, who controls, any such
                                underwriter within the meaning of the 1933 Act
                                or the 1934 Act (each, an "INDEMNIFIED PERSON"),
                                subject to Section 6(d) with respect to the
                                number of legal counsel, against any losses,
                                claims, damages, liabilities, judgments, fines,
                                penalties, charges, costs, attorneys' fees,
                                amounts paid in settlement or expenses, joint or
                                several, (collectively, "INDEMNIFIED DAMAGES")
                                incurred in investigating, preparing or
                                defending any action, claim, suit, inquiry,
                                proceeding, investigation or appeal taken from
                                the foregoing by or before any court or
                                governmental, administrative or other regulatory
                                agency, body or the SEC, whether pending or
                                threatened, whether or not an indemnified party
                                is or may



                                       12
<PAGE>

                                be a party thereto (collectively, "CLAIMS"), to
                                which any of them may become subject insofar as
                                such Claims (or actions or proceedings, whether
                                commenced or threatened, in respect thereof)
                                arise out of or are based upon: (i) any untrue
                                statement or alleged untrue statement of a
                                material fact in a Registration Statement or any
                                post-effective amendment thereto or in any
                                filing made in connection with the qualification
                                of the offering under the securities or other
                                "blue sky" laws of any jurisdiction in which
                                Registrable Securities are offered, or the
                                omission or alleged omission to state a material
                                fact required to be stated therein or necessary
                                to make the statements therein not misleading,
                                (ii) any untrue statement or alleged untrue
                                statement of a material fact contained in any
                                preliminary prospectus if used prior to the
                                effective date of such Registration Statement,
                                or contained in the final prospectus (as amended
                                or supplemented, if the Company files any
                                amendment thereof or supplement thereto with the
                                SEC) or the omission or alleged omission to
                                state therein any material fact necessary to
                                make the statements made therein, in light of
                                the circumstances under which the statements
                                therein were made, not misleading, or (iii) any
                                violation or alleged violation by the Company of
                                the 1933 Act, the 1934 Act, any state securities
                                law, or any rule or regulation thereunder
                                relating to the offer or sale of the Registrable
                                Securities pursuant to a Registration Statement
                                (the matters in the foregoing clauses (i)
                                through (iii) being, collectively,
                                "VIOLATIONS"). Subject to the restrictions set
                                forth in Section 6(d) with respect to the number
                                of legal counsel, the Company shall reimburse
                                each Indemnified Person promptly as such
                                expenses are incurred and are due and payable,
                                for any reasonable legal fees or other
                                reasonable expenses incurred by them in
                                connection with investigating or defending any
                                such Claim. Notwithstanding anything to the
                                contrary contained herein, the indemnification
                                agreement contained in this Section 6(a): (i)
                                shall not apply to a Claim by an Indemnified
                                Person arising out of or based upon a Violation
                                which occurs in reliance upon and in conformity
                                with information furnished in writing to the
                                Company by such Indemnified Person expressly for
                                use in connection with the preparation of the
                                Registration Statement or any such amendment
                                thereof or supplement thereto, if such
                                prospectus was timely made available by the
                                Company pursuant to Section 3(d); (ii) with
                                respect to any preliminary prospectus, shall not
                                inure to the benefit of any such Person from
                                whom the



                                       13
<PAGE>

                                Person asserting any such Claim purchased the
                                Registrable Securities that are the subject
                                thereof (or to the benefit of any Person
                                controlling such Person) if the untrue statement
                                or omission of material fact contained in the
                                preliminary prospectus was corrected in the
                                prospectus, as then amended or supplemented, if
                                such prospectus was timely made available by the
                                Company pursuant to Section 3(d), and the
                                Indemnified Person was promptly advised in
                                writing not to use the incorrect prospectus
                                prior to the use giving rise to a violation and
                                such Indemnified Person, notwithstanding such
                                advice, used it; (iii) shall not be available to
                                the extent such Claim is based on a failure of
                                the Investor to deliver or to cause to be
                                delivered the prospectus made available by the
                                Company, if such prospectus was timely made
                                available by the Company pursuant to Section
                                3(d); and (iv) shall not apply to amounts paid
                                in settlement of any Claim if such settlement is
                                effected without the prior written consent of
                                the Company, which consent shall not be
                                unreasonably withheld. Such indemnity shall
                                remain in full force and effect regardless of
                                any investigation made by or on behalf of the
                                Indemnified Person and shall survive the
                                transfer of the Registrable Securities by the
                                Investors pursuant to Section 10.

                        b.      In connection with any Registration Statement in
                                which an Investor is participating, each such
                                Investor agrees to severally and not jointly
                                indemnify, hold harmless and defend, to the same
                                extent and in the same manner as is set forth in
                                Section 6(a), the Company, each of its
                                directors, each of its officers who signs the
                                Registration Statement, its employees and
                                agents, and each Person, if any, who controls
                                the Company within the meaning of the 1933 Act
                                or the 1934 Act (collectively and together with
                                an Indemnified Person, an "INDEMNIFIED PARTY"),
                                against any Claim or Indemnified Damages to
                                which any Indemnified Party may become subject,
                                under the 1933 Act, the 1934 Act or otherwise,
                                insofar as such Claim or Indemnified Damages
                                arise out of or are based upon any Violation, in
                                each case to the extent, and only to the extent,
                                that such Violation occurs in reliance upon and
                                in conformity with written information furnished
                                to the Company by such Investor expressly for
                                use in connection with such Registration
                                Statement; and, subject to Section 6(d), such
                                Investor will reimburse any legal or other
                                expenses reasonably incurred by them in
                                connection with investigating or defending any
                                such Claim; provided,



                                       14
<PAGE>

                                however, that the indemnity agreement contained
                                in this Section 6(b) and the agreement with
                                respect to contribution contained in Section 7
                                shall not apply to amounts paid in settlement of
                                any Claim if such settlement is effected without
                                the prior written consent of such Investor,
                                which consent shall not be unreasonably
                                withheld; provided, further, however, that the
                                Investor shall be liable under this Section 6(b)
                                for only that amount of a Claim or Indemnified
                                Damages as does not exceed the net proceeds to
                                such Investor as a result of the sale of
                                Registrable Securities pursuant to such
                                Registration Statement. Such indemnity shall
                                remain in full force and effect regardless of
                                any investigation made by or on behalf of such
                                Indemnified Party and shall survive the transfer
                                of the Registrable Securities by the Investors
                                pursuant to Section 10. Notwithstanding anything
                                to the contrary contained herein, the
                                indemnification agreement contained in this
                                Section 6(b) with respect to any preliminary
                                prospectus shall not inure to the benefit of any
                                Indemnified Party if the untrue statement or
                                omission of material fact contained in the
                                preliminary prospectus was corrected on a timely
                                basis in the prospectus, as then amended or
                                supplemented, or the Indemnified Party failed to
                                utilize such corrected prospectus.

                        c.      The Company shall be entitled to receive
                                indemnities from underwriters, selling brokers,
                                dealer managers and similar securities industry
                                professionals participating in any distribution,
                                to the same extent as provided above, with
                                respect to information such Persons so furnished
                                in writing expressly for inclusion in the
                                Registration Statement.

                        d.      Promptly after receipt by an Indemnified Person
                                or Indemnified Party under this Section 6 of
                                notice of the commencement of any action or
                                proceeding (including any governmental action or
                                proceeding) involving a Claim, such Indemnified
                                Person or Indemnified Party shall, if a Claim in
                                respect thereof is to be made against any
                                indemnifying party under this Section 6, deliver
                                to the indemnifying party a written notice of
                                the commencement thereof, and the indemnifying
                                party shall have the right to participate in,
                                and, to the extent the indemnifying party so
                                desires, jointly with any other indemnifying
                                party similarly noticed, to assume control of
                                the defense thereof with counsel mutually
                                satisfactory to the indemnifying party and the
                                Indemnified Person or the Indemnified Party, as
                                the case may be; provided, however, that an
                                indemnifying



                                       15
<PAGE>

                                party shall not be entitled to assume such
                                defense and an Indemnified Person or Indemnified
                                Party shall have the right to retain its own
                                counsel with the reasonable fees and expenses to
                                be paid by the indemnifying party, if, in the
                                reasonable opinion of counsel retained by the
                                indemnifying party, the representation by such
                                counsel of the Indemnified Person or Indemnified
                                Party and the indemnifying party would be
                                inappropriate due to actual or potential
                                differing interests between such Indemnified
                                Person or Indemnified Party and any other party
                                represented by such counsel in such proceeding,
                                or the actual or potential defendants in, or
                                targets of, any such action include both the
                                Indemnified Person or Indemnified Party and the
                                indemnifying party, and any such Indemnified
                                Person or Indemnified Party reasonably
                                determines that there may be legal defenses
                                available to such Indemnified Person to such
                                indemnifying party. The indemnifying party shall
                                pay reasonable fees for only one (1) separate
                                legal counsel for the Indemnified Person or
                                Indemnified Party, as applicable, and such legal
                                counsel shall be selected by Investors holding a
                                majority in interest of the Registrable
                                Securities included in the Registration
                                Statement to which the Claim relates, if the
                                Investors are entitled to indemnification
                                hereunder, or by the Company, if the Company is
                                entitled to indemnification hereunder, as
                                applicable. The Indemnified Party or Indemnified
                                Person shall cooperate fully with the
                                indemnifying party in connection with any
                                negotiation or defense of any such action or
                                claim by the indemnifying party and shall
                                furnish to the indemnifying party all
                                information reasonably available to the
                                Indemnified Party or Indemnified Person which
                                relates to such action or claim. The
                                indemnifying party shall keep the Indemnified
                                Party or Indemnified Person fully apprised at
                                all times as to the status of the defense or any
                                settlement negotiations with respect thereto. No
                                indemnifying party shall be liable for any
                                settlement of any action, claim or proceeding
                                effected without its written consent; provided,
                                however, that the indemnifying party shall not
                                unreasonably withhold, delay or condition its
                                consent. No indemnifying party shall, without
                                the consent of the Indemnified Party or
                                Indemnified Person, consent to entry of any
                                judgment or enter into any settlement or other
                                compromise which does not include as an
                                unconditional term thereof the giving by the
                                claimant or plaintiff to such Indemnified Party
                                or Indemnified Person of a release from all
                                liability in respect to such claim or
                                litigation. Following



                                       16
<PAGE>

                                indemnification as provided for hereunder, the
                                indemnifying party shall be subrogated to all
                                rights of the Indemnified Party or Indemnified
                                Person with respect to all third parties, firms
                                or corporations relating to the matter for which
                                indemnification has been made. The failure to
                                deliver written notice to the indemnifying party
                                within a reasonable time of the commencement of
                                any such action shall not relieve such
                                indemnifying party of any liability to the
                                Indemnified Person or Indemnified Party under
                                this Section 6, except to the extent that the
                                indemnifying party is prejudiced in its ability
                                to defend such action.

                        e.      The indemnification required by this Section 6
                                shall be made by periodic payments of the amount
                                thereof during the course of the investigation
                                or defense, as and when bills are received or
                                Indemnified Damages are incurred.

                        f.      The indemnity agreements contained herein shall
                                be in addition to (i) any cause of action or
                                similar right of the Indemnified Party or
                                Indemnified Person against the indemnifying
                                party or others, and (ii) any liabilities the
                                indemnifying party may be subject to pursuant to
                                the law.

                7.      CONTRIBUTION

        To the extent any indemnification by an indemnifying party is prohibited
or limited by law, the indemnifying party agrees to make the maximum
contribution with respect to any amounts for which it would otherwise be liable
under Section 6 to the fullest extent permitted by law; provided, however, that:
(i) no seller of Registrable Securities guilty of fraudulent misrepresentation
(within the meaning of Section 11(f) of the 1933 Act) shall be entitled to
contribution from any seller of Registrable Securities who was not guilty of
fraudulent misrepresentation; and (ii) contribution by any seller of Registrable
Securities shall be limited in amount to the net amount of proceeds received by
such seller from the sale of such Registrable Securities.

                8.      REPORTS UNDER THE 1934 ACT

        With a view to making available to the Investors the benefits of Rule
144 promulgated under the 1933 Act or any other similar rule or regulation of
the SEC that may at any time permit the Investors to sell securities of the
Company to the public without registration ("RULE 144"), the Company agrees to:

                        a.      make and keep public information available, as
                                those terms are understood and defined in Rule
                                144;

                        b.      file with the SEC in a timely manner all reports
                                and other documents required of the Company
                                under the 1933 Act and the 1934 Act so long as
                                the Company remains subject



                                       17
<PAGE>

                                to such requirements (it being understood that
                                nothing herein shall limit the Company's
                                obligations under Section 4(c) of the Securities
                                Purchase Agreement) and the filing of such
                                reports and other documents is required for the
                                applicable provisions of Rule 144; and

                        c.      furnish to each Investor so long as such
                                Investor owns Registrable Securities, promptly
                                upon request, (i) a written statement by the
                                Company that it has complied with the reporting
                                requirements of Rule 144, the 1933 Act and the
                                1934 Act, (ii) a copy of the most recent annual
                                or quarterly report of the Company and such
                                other reports and documents so filed by the
                                Company, and (iii) such other information as may
                                be reasonably requested to permit the investors
                                to sell such securities pursuant to Rule 144
                                without registration.

                9.      LIQUIDATED DAMAGES

        If: (a) any Registration Statement required to be filed pursuant to
Section 2(a) is not filed on or prior to the Filing Date, (b) unless waived by
the Investors, the Company files such Registration Statement without affording
Legal Counsel the opportunity to review and comment on the same as required by
Section 3(c), or (c) the Company fails to file with the SEC a request for
acceleration in accordance with Rule 461 promulgated under the 1933 Act, within
five (5) business days after the Company is advised orally or in writing by the
SEC that the SEC will not review or has no further comments concerning the
Registration Statement, or (d) a Registration Statement filed hereunder is not
declared effective by the SEC on or prior to the Effectiveness Date, or (e)
after a Registration Statement is filed with and declared effective by the SEC,
such Registration Statement ceases to be effective as to all Registrable
Securities to which it is required to relate at any time prior to the expiration
of the Registration Period without being succeeded within ten (10) trading days,
or if it would be Materially Detrimental, twenty (20) trading days, by an
amendment to such Registration Statement or by a subsequent Registration
Statement filed with and declared effective by the SEC, or (f) an amendment to a
Registration Statement is not filed by the Company with the SEC within ten (10)
trading days, or if it would be Materially Detrimental, twenty (20) trading
days, of the SEC's notifying the Company that such amendment is required in
order for such Registration Statement to be declared or remain effective, or (g)
the Common Stock is not listed or quoted, or is suspended from trading, on
Nasdaq for a period of ten (10) trading days in any 12 month period (which need
not be consecutive trading days), (any such failure or breach being referred to
as an "REGISTRATION DEFAULT," and, (w) for purposes of clause (a), (b) or (d),
the date on which such Registration Default occurs, (x) for purposes of clause
(c), the date on which such five (5) day period is exceeded, (y) for purposes of
clauses (e) and (f) the date on which the applicable trading day-period is
exceeded, or (z) for purposes of clause (g) the date on which such ten (10)
trading day period is exceeded, being referred to as an "EVENT DATE"), then the
Company shall pay to each Holder an amount, in cash, as liquidated damages
("LIQUIDATED DAMAGES")



                                       18
<PAGE>

(x) upon the occurrence of a Registration Default, an amount equal to one
percent (1%) of the aggregate Price Per Unit of the Units then held by such
Buyer, and (y) if the Registration Default has not been cured by the first month
anniversary following the date of the Registration Default, an amount equal to
one percent (1%) of the aggregate Price Per Unit of the Units then held by such
Buyer and (z) on each monthly anniversary thereafter until the Registration
Default has been cured, an amount equal to one percent (1%) of the aggregate
Price Per Unit of the Units then held by such Buyer; provided, however, that all
periods referred to in clauses (y) and (z) above shall be tolled during delays
caused by the action or inaction of any Buyer, and the Company shall have no
liability in respect of any such delay. The Liquidated Damages payable pursuant
hereto shall be payable within five (5) business days following the date of the
Registration Default or the monthly anniversary thereof, as the case may be.
Notwithstanding anything to the contrary contained herein, (x) Liquidated
Damages shall not be payable under this Section 9 for more than one Registration
Default occurring or existing at any one time, (y) no Liquidated Damages shall
be payable under this Section 9 in respect of any Registration Default which
also constitutes a Company Violation under the Securities Purchase Agreement or
is an exception from the liquidated damages provisions contained in Section 8 of
the Securities Purchase Agreement, or (z) that the Company shall have no
liability to any Investor for any Liquidated Damages at the occurrence of a
Registration Default or thereafter if the Company's violation of any such
material provision or failure to fulfill such material obligations is caused by
or results from any action or inaction of any such Investor or any other
Investor.

                10.     ASSIGNMENT OF REGISTRATION RIGHTS

        The rights under this Agreement shall be automatically assignable by the
Investors to any transferee of all or any portion of Registrable Securities if:
(i) the Investor agrees in writing with the transferee or assignee to assign
such rights, and a copy of such agreement is furnished to the Company within a
reasonable time after such assignment; (ii) the Company is, within a reasonable
time after such transfer or assignment, furnished with written notice of (a) the
name and address of such transferee or assignee, and (b) the securities with
respect to which such registration rights are being transferred or assigned;
(iii) immediately following such transfer or assignment the further disposition
of such securities by the transferee or assignee is restricted under the 1933
Act and applicable state securities laws; provided, however, that the transferee
or assignee may subsequently transfer or assign all or any portion of the
Registrable Securities if an exemption from registration under the 1933 Act is
applicable to such transfer or assignment; (iv) at or before the time the
Company receives the written notice contemplated by clause (ii) of this sentence
the transferee or assignee agrees in writing with the Company to be bound by all
of the provisions contained herein; and (v) such transfer shall have been made
in accordance with the applicable requirements of the Securities Purchase
Agreement.



                                       19
<PAGE>

                11.     AMENDMENT OF REGISTRATION RIGHTS

        Provisions of this Agreement may be amended and the observance thereof
may be waived (either generally or in a particular instance and either
retroactively or prospectively), only with the written consent of the Company
and Investors who then hold two-thirds (2/3) of the Registrable Securities. Any
amendment or waiver effected in accordance with this Section 11 shall be binding
upon each Investor and the Company. No such amendment shall be effective to the
extent that it applies to less than all of the holders of the Registrable
Securities. No consideration shall be offered or paid to any Person to amend or
consent to a waiver or modification of any provision of any of this Agreement
unless the same consideration also is offered to all of the parties to this
Agreement.

                12.     MISCELLANEOUS

                        a.      A Person is deemed to be a holder of Registrable
                                Securities whenever such Person owns or is
                                deemed to own of record such Registrable
                                Securities. If the Company receives conflicting
                                instructions, notices or elections from two or
                                more Persons with respect to the same
                                Registrable Securities, the Company shall act
                                upon the basis of instructions, notice or
                                election received from the registered owner of
                                such Registrable Securities.

                        b.      Any notices, consents, waivers or other
                                communications required or permitted to be given
                                under the terms of this Agreement must be in
                                writing and will be deemed to have been
                                delivered: (i) upon receipt, when delivered
                                personally; (ii) upon receipt, when sent by
                                facsimile (provided confirmation of transmission
                                is mechanically or electronically generated and
                                kept on file by the sending party); or (iii) one
                                (1) business day after deposit with a nationally
                                recognized overnight delivery service, in each
                                case properly addressed to the party to receive
                                the same. The addresses and facsimile numbers
                                for such communications shall be:

        If to the Company:

                EntreMed, Inc.
                9640 Medical Center Drive
                Rockville, MD 20850
                Telephone:   (301) 217-9858
                Facsimile:   (301) 217-9594
                Attention:   John W. Holaday, Ph.D.



                                       20
<PAGE>

        With a copy to:

                Arnold & Porter
                1600 Tysons Boulevard, Ste. 900
                McLean, VA 22102
                Telephone:   (703) 720-7005
                Facsimile:   (703) 720-7399
                Attention:   Robert B. Ott, Esq.

        If to Legal Counsel:

                Robinson Silverman Pearce Aronsohn & Berman LLP
                1290 Avenue of the Americas
                New York, NY 10104
                Telephone:   (212) 541-2000
                Facsimile:   (212) 541-4630
                Attention:   Eric L. Cohen

If to a Buyer, to it at the address and facsimile number set forth on the
Schedule of Buyers attached hereto, with copies to such Buyer's representatives
as set forth on the Schedule of Buyers, or at such other address and/or
facsimile number and/or to the attention of such other Person as the recipient
party has specified by written notice given to each other party five (5) days
prior to the effectiveness of such change.

                        c.      Failure of any party to exercise any right or
                                remedy under this Agreement or otherwise, or
                                delay by a party in exercising such right or
                                remedy, shall not operate as a waiver thereof.

                        d.      This Agreement shall be governed by and
                                construed in all respects by the internal laws
                                of the State of New York (except for the proper
                                application of the United States federal
                                securities laws), without giving effect to any
                                choice of law or conflict of law provision or
                                rule (whether of the State of New York or any
                                other jurisdictions) that would cause the
                                application of the laws of any jurisdictions
                                other than the State of New York. Each party
                                hereby irrevocably submits to the exclusive
                                jurisdiction of the state and federal courts
                                sitting the City of New York, for the
                                adjudication of any dispute hereunder. If any
                                provision of this Agreement shall be invalid or
                                unenforceable in any jurisdiction, such
                                invalidity or unenforceability shall not affect
                                the validity or enforceability of the remainder
                                of this Agreement in that jurisdiction or the
                                validity or enforceability of any provision of
                                this Agreement in any other jurisdiction. In any
                                suit or action to enforce the provisions of this
                                Agreement, the prevailing party shall be
                                entitled to be



                                       21
<PAGE>

                                reimbursed for all reasonable legal fees and
                                expenses incurred by such party in connection
                                with such suit or action.

                        e.      This Agreement, the Securities Purchase
                                Agreement and the Warrants constitute the entire
                                agreement among the parties hereto with respect
                                to the subject matter hereof and thereof. There
                                are no restrictions, promises, warranties or
                                undertakings, other than those set forth or
                                referred to herein and therein. This Agreement,
                                the Securities Purchase Agreement and the
                                Warrants supersede all prior agreements and
                                understandings among the parties hereto with
                                respect to the subject matter hereof and
                                thereof.

                        f.      Subject to the requirements of Section 10, this
                                Agreement shall inure to the benefit of and be
                                binding upon the permitted successors and
                                assigns of each of the parties hereto.

                        g.      The headings in this Agreement are for
                                convenience of reference only and shall not
                                limit or otherwise affect the meaning hereof.

                        h.      This Agreement may be executed in identical
                                counterparts, each of which shall be deemed an
                                original but all of which shall constitute one
                                and the same agreement. This Agreement, once
                                executed by a party, may be delivered to the
                                other party hereto by facsimile transmission of
                                a copy of this Agreement bearing the signature
                                of the party so delivering this Agreement.

                        i.      Each party shall do and perform, or cause to be
                                done and performed, all such further acts and
                                things, and shall execute and deliver all such
                                other agreements, certificates, instruments and
                                documents, as the other party may reasonably
                                request in order to carry out the intent and
                                accomplish the purposes of this Agreement and
                                the consummation of the transactions
                                contemplated hereby.

                        j.      All consents and other determinations to be made
                                by the Investors pursuant to this Agreement
                                shall be made, unless otherwise specified in
                                this Agreement, by Investors holding a majority
                                of the Registrable Securities, determined as if
                                all of the Warrants then outstanding have been
                                converted into Registrable Securities without
                                regard to any limitation on exercise of the
                                Warrants.



                                       22
<PAGE>

                        k.      The language used in this Agreement will be
                                deemed to be the language chosen by the parties
                                to express their mutual intent and no rules of
                                strict construction will be applied against any
                                party.

                        l.      This Agreement is intended for the benefit of
                                the parties hereto and their respective
                                permitted successors and assigns, and is not for
                                the benefit of, nor may any provision hereof be
                                enforced by, any other Person.

                            [signature pages follow]



                                       23
<PAGE>

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


                                        COMPANY:

                                        ENTREMED, INC.


                                        By:    /s/ John W. Holaday, PhD
                                           ---------------------------------
                                        Name:  John W. Holaday, PhD
                                        Title: Chairman and CEO










<PAGE>



                                        BUYER:

                                        CRANSHIRE CAPITAL, L.P.


                                        By:   Downsview Capital, Inc.,
                                              the General Partner

                                              By:    /s/ Mitchell P. Kopin
                                                  ------------------------------
                                              Name:  Mitchell P. Kopin
                                              Title: President


                                        BUYER:

                                        EURAM CAP STRAT "A" FUND LIMITED

                                        By:   JMJ Capital, Inc., the Investment
                                              Manager


                                              By:   /s/ Mitchell P. Kopin
                                                 -------------------------------
                                              Name:     Mitchell P. Kopin
                                              Title:    President


                                        BUYER:

                                        CLEVELAND OVERSEAS LTD.

                                        By:  Primeway S.A., Director

                                        By:    /s/ Beat Kunz
                                           -----------------
                                        Name:      Beat Kunz


                                        BUYER:

                                        WINCHESTER GLOBAL TRUST
                                        COMPANY LIMITED AS TRUSTEE FOR
                                        CADUCEUS CAPITAL TRUST



                                        By:    /s/ Samuel D. Isaly
                                           -------------------------------------
                                        Name:  Samuel D. Isaly
                                        Title: Managing Partner,
                                               OriMed Advisors LLC


                                        BUYER:

                                        CADUCEUS CAPITAL II, L.P.



                                        By:    /s/ Samuel D. Isaly
                                           -------------------------------------
                                        Name:  Samuel D. Isaly
                                        Title: Managing Partner,
                                               OriMed Advisors LLC



<PAGE>

                                        BUYER:

                                        PW EUCALYPTUS FUND, L.L.C.



                                        By:    /s/ Samuel D. Isaly
                                           -------------------------------------
                                        Name:  Samuel D. Isaly
                                        Title: Managing Partner,
                                               OriMed Advisors LLC





                                        BUYER:

                                        PW EUCALYPTUS FUND, LTD.


                                        By:    /s/ Samuel D. Isaly
                                           -------------------------------------
                                        Name:  Samuel D. Isaly
                                        Title: Managing Partner,
                                               OriMed Advisors LLC




                                        BUYER:

                                        DMG LEGACY FUND LLC
                                        By:  DMG Advisors LLC, Managing Member


                                        By:     /s/ Andrew Wilder
                                           -------------------------------------
                                        Name:       Andrew Wilder
                                        Title:      Chief Financial Officer



                                        BUYER:

                                        DMG LEGACY INSTITUTIONAL FUND LLC
                                        By:  DMG Advisors LLC, Managing Member


                                        By:    /s/ Andrew Wilder
                                           -------------------------------------
                                        Name:      Andrew Wilder
                                        Title:     Chief Financial Officer



                                        BUYER:

                                        DMG LEGACY INTERNATIONAL LTD.
                                        By:  DMG Advisors LLC, Investment
                                             Advisor


                                        By:    /s/ Andrew Wilder
                                           -------------------------------------
                                        Name:      Andrew Wilder
                                        Title:     Chief Financial Officer


<PAGE>

                                        BUYER:

                                        EDJ Limited



                                        By:    /s/ Jeffrey Porter
                                           -------------------------------------
                                        Name:      Jeffrey Porter
                                        Title:     Trading Advisor



                                        BUYER:

                                        Arnold S. Gumowitz


                                        By:   /s/ Arnold S. Gumowitz
                                           -------------------------------------
                                        Name:     Arnold S. Gumowitz



                                        BUYER:

                                        MAPLE BANK GMBH-MILAN BRANCH

                                        By:    /s/ Myles Marmion
                                           -------------------------------------
                                        Name:      M.C. Marmion
                                        Title:     Authorized Signatory



                                        BUYER:

                                        PORTER PARTNERS, L.P.

                                        By:    /s/ Jeffrey Porter
                                           -------------------------------------
                                        Name:      Jeffrey Porter
                                        Title:     General Partner




                                        BUYER:

                                        S.A.C. CAPITAL ASSOCIATES, LLC
                                        BY:  S.A.C. Capital Advisors, LLC

                                        By:    /s/ Peter Nussbaum
                                           -------------------------------------
                                        Name:      Peter Nussbaum
                                        Title:     General Counsel


<PAGE>

                                        BUYER:

                                        THOMAS SERVICE


                                        By:   /s/ Thomas Service
                                           -------------------------------------
                                        Name:     Thomas Service



                                        BUYER:

                                        STEELHEAD INVESTMENTS, LTD.


                                        By:    /s/ Kevin O'Neal
                                           -------------------------------------
                                        Name:      Kevin O'Neal
                                        Title:     Authorized Signatory



                                        BUYER:

                                        VERTICAL INTERNATIONAL LTD.


                                        By:    /s/ Kenneth Henderson
                                           -------------------------------------
                                        Name:      Kenneth Henderson
                                        Title:     Authorized Signatory



                                        BUYER:

                                        ZLP MASTER FUND, LTD


                                        By:    /s/ Stuart J. Zimmer
                                           -------------------------------------
                                        Name:      Stuart J. Zimmer
                                        Title:     Director





<PAGE>

                                                                       EXHIBIT A

                         FORM OF NOTICE OF EFFECTIVENESS
                            OF REGISTRATION STATEMENT

[TRANSFER AGENT]

Attn:
     ---------------------------

        Re: EntreMed, Inc.

Ladies and Gentlemen:

        We are counsel to EntreMed, Inc., a Delaware corporation (the
"COMPANY"), and have represented the Company in connection with that certain
Securities Purchase Agreement (the "PURCHASE AGREEMENT") entered into by and
among the Company and the buyers named therein (collectively, the "HOLDERS")
pursuant to which the Company issued to the Holders shares of its common stock,
par value $.01 per share (the "COMMON SHARES"), and Warrants exercisable into
its Common Stock (the "WARRANT SHARES"). Pursuant to the Purchase Agreement, the
Company also has entered into a Registration Rights Agreement with the Holders
(the "REGISTRATION RIGHTS AGREEMENT") pursuant to which the Company agreed,
among other things, to register the Registrable Securities (as defined in the
Registration Rights Agreement), including the Common Shares and Warrant Shares,
under the Securities Act of 1933, as amended (the "1933 ACT"). In connection
with the Company's obligations under the Registration Rights Agreement, on
_________, 2001, the Company filed a Registration Statement on Form S-3 (File
No. _____________) (the "REGISTRATION STATEMENT") with the Securities and
Exchange Commission (the "SEC") relating to the Registrable Securities which
names each of the Holders as a selling stockholder thereunder.

        In connection with the foregoing, we advise you that a member of the
SEC's staff has advised us [by telephone/in writing] that the SEC has entered an
order declaring the Registration Statement effective under the 1933 Act at
[ENTER TIME OF EFFECTIVENESS] on [ENTER DATE OF EFFECTIVENESS] and we have no
knowledge, after telephonic inquiry of a member of the SEC's staff, that any
stop order suspending its effectiveness has been issued or that any proceedings
for that purpose are pending before, or threatened by, the SEC and the
Registrable Securities are available for resale under the 1933 Act pursuant to
the Registration Statement.

                                        Very truly yours,
                                        [ISSUER'S COUNSEL]

                                        By:
                                           ------------------------------

cc:     [Legal Counsel]



<PAGE>

                                                                       EXHIBIT B

                              PLAN OF DISTRIBUTION

        The Selling Stockholders and any of their pledgees, assignees and
successors-in-interest may, from time to time, sell any or all of their shares
of Common Stock on any stock exchange, market or trading facility on which the
shares are traded or in private transactions. These sales may be at fixed or
negotiated prices. The Selling Stockholders may use any one or more of the
following methods when selling shares:

        ordinary brokerage transactions and transactions in which the
        broker-dealer solicits purchasers;

        block trades in which the broker-dealer will attempt to sell the shares
        as agent but may position and resell a portion of the block as principal
        to facilitate the transaction;

        purchases by a broker-dealer as principal and resale by the
        broker-dealer for its account;

        an exchange distribution in accordance with the rules of the applicable
        exchange;

        privately negotiated transactions;

        short sales;

        broker-dealers may agree with the Selling Stockholders to sell a
        specified number of such shares at a stipulated price per share;

        a combination of any such methods of sale; and

        any other method permitted pursuant to applicable law.

        The Selling Stockholders may also sell shares under Rule 144 under the
Securities Act, if available, rather than under this prospectus.

        The Selling Stockholders may also engage in short sales against the box,
puts and calls and other transactions in securities of the Company or
derivatives of Company securities and may sell or deliver shares in connection
with these trades. The Selling Stockholders may pledge their shares to their
brokers under the margin provisions of customer agreements. If a Selling
Stockholder defaults on a margin loan, the broker may, from time to time, offer
and sell the pledged shares.

        Broker-dealers engaged by the Selling Stockholders may arrange for other
brokers-dealers to participate in sales. Broker-dealers may receive commissions
or discounts from the Selling Stockholders (or, if any broker-dealer acts as
agent for the purchaser of shares, from the purchaser) in amounts to be
negotiated. The Selling Stockholders do not expect these commissions and
discounts to exceed what is customary in the types of transactions involved.



                                      B-1

<PAGE>

        The Selling Stockholders and any broker-dealers or agents that are
involved in selling the shares may be deemed to be "underwriters" within the
meaning of the Securities Act in connection with such sales. In such event, any
commissions received by such broker-dealers or agents and any profit on the
resale of the shares purchased by them may be deemed to be underwriting
commissions or discounts under the Securities Act.

        The Company is required to pay all fees and expenses incident to the
registration of the shares, including fees and disbursements of counsel to the
Selling Stockholders. The Company has agreed to indemnify the Selling
Stockholders against certain losses, claims, damages and liabilities, including
liabilities under the Securities Act.

        The Selling Stockholders may from time to time pledge or grant a
security interest in some or all of the Shares or Warrants or shares of Common
Stock issuable upon exercise of Warrants owned by them and, if they default in
the performance of their secured obligations, the pledgees or secured parties
may offer and sell the shares of common stock from time to time under this
prospectus, or under an amendment to this prospectus under Rule 424(b)(3) or
other applicable provision of the Securities Act amending the list of Selling
Stockholders to include the pledgee, transferee or other successors in interest
as Selling Stockholders under this prospectus.

        The Selling Stockholders also may transfer the shares of common stock in
other circumstances, in which case the transferees, pledgees or other successors
in interest will be the selling beneficial owners for purposes of this
prospectus.



                                      B-2