Exhibit 10.3
                          REGISTRATION RIGHTS AGREEMENT


     This Registration  Rights Agreement (this  "Agreement") is made and entered
into  as of  July  10,  2003,  by and  among  Cytogen  Corporation,  a  Delaware
corporation  (the  "Company"),  and  the  investors  signatory  hereto  (each  a
"Purchaser" and collectively, the "Purchasers").

     This Agreement is made pursuant to the Securities Purchase Agreement, dated
as of the date  hereof  among the  Company  and the  Purchasers  (the  "Purchase
Agreement").

     The Company and the Purchasers hereby agree as follows:

     1.  Definitions.  Capitalized  terms used and not otherwise  defined herein
that are defined in the Purchase  Agreement  shall have the meanings  given such
terms in the Purchase Agreement. As used in this Agreement,  the following terms
shall have the following meanings:

               "Effectiveness   Date"   means,   with  respect  to  the  initial
          Registration  Statement  required  to be  filed  hereunder,  the  90th
          calendar day  following  the Closing  Date (or the 120th  calendar day
          following the Closing Date in the event of a review by the  Commission
          or in  the  event  the  Commission  delays  the  effectiveness  of the
          Registration  Statement due to a review of the  Company's  outstanding
          confidentiality  treatment  applications)  and  with  respect  to  any
          additional  Registration Statements required pursuant to Section 2(c),
          the 90th  calendar day  following  the date on which the Company first
          knows,  or  reasonably   should  have  known,   that  such  additional
          Registration  Statement is required  hereunder (or the 120th  calendar
          day following the date on which the Company first knows, or reasonably
          should have known,  that such  additional  Registration  Statement  is
          required  hereunder in the event of a review by the  Commission  or in
          the event the Commission delays the effectiveness of such Registration
          Statement due to a review of the Company's outstanding confidentiality
          treatment applications).

               "Effectiveness  Period"  shall  have  the  meaning  set  forth in
          Section 2(a).

               "Filing  Date" means,  with  respect to the initial  Registration
          Statement  required  to be  filed  hereunder,  the 30th  calendar  day
          following  the  Closing  Date  and,  with  respect  to any  additional
          Registration  Statements  which may be  required  pursuant  to Section
          2(c),  the 30th  calendar day  following the date on which the Company
          first  knows,  or  reasonably  should have known that such  additional
          Registration Statement is required hereunder.

               "Holder" or  "Holders"  means the holder or holders,  as the case
          may be, from time to time of Registrable Securities.

               "Indemnified  Party"  shall have the meaning set forth in Section
          5(c).

               "Indemnifying  Party" shall have the meaning set forth in Section
          5(c).

               "Losses" shall have the meaning set forth in Section 5(a).

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               "Proceeding"  means an  action,  claim,  suit,  investigation  or
          proceeding (including, without limitation, an investigation or partial
          proceeding, such as a deposition), whether commenced or threatened.

               "Prospectus"  means the  prospectus  included  in a  Registration
          Statement (including,  without limitation,  a prospectus that includes
          any information  previously omitted from a prospectus filed as part of
          an  effective  registration  statement  in  reliance  upon  Rule  430A
          promulgated  under the Securities  Act), as amended or supplemented by
          any prospectus  supplement,  with respect to the terms of the offering
          of any portion of the Registrable Securities covered by a Registration
          Statement, and all other amendments and supplements to the Prospectus,
          including post-effective  amendments, and all material incorporated by
          reference  or  deemed  to  be   incorporated   by  reference  in  such
          Prospectus.

               "Registrable  Securities"  means the  Shares,  together  with any
          securities issued or issuable upon any stock split,  dividend or other
          distribution,  recapitalization  or similar  event with respect to the
          foregoing.

               "Registration Statement" means a Registration Statements required
          to be filed  hereunder,  including  (in  each  case)  the  Prospectus,
          amendments  and   supplements  to  such   registration   statement  or
          Prospectus, including pre- and post-effective amendments, all exhibits
          thereto,  and all material  incorporated  by reference or deemed to be
          incorporated by reference in such registration statement.

               "Rule 415" means Rule 415 promulgated by the Commission  pursuant
          to the Securities  Act, as such Rule may be amended from time to time,
          or any similar rule or regulation  hereafter adopted by the Commission
          having substantially the same effect as such Rule.

               "Rule 424" means Rule 424 promulgated by the Commission  pursuant
          to the Securities  Act, as such Rule may be amended from time to time,
          or any similar rule or regulation  hereafter adopted by the Commission
          having substantially the same effect as such Rule.

               "Securities Act" means the Securities Act of 1933, as amended.

               "Shares"  solely  for the  purpose  of this  Agreement  means the
          Shares  (as  defined  in the  Purchase  Agreement)  together  with the
          Warrant Shares issuable upon exercise of the Warrants.

     2. Registration.

               (a) On or  prior to each  Filing  Date,  the  Company  shall  use
          commercially   reasonable   efforts  to  prepare  and  file  with  the
          Commission a Registration Statement covering the resale of 100% of the
          Registrable  Securities  for an  offering  to be made on a  continuous
          basis  pursuant  to  Rule  415.  A  Registration   Statement  required
          hereunder  shall be on Form S-3  (except  if the  Company  is not then
          eligible to register  for resale the  Registrable  Securities  on Form
          S-3, in which case such registration  shall be on another  appropriate
          form in accordance herewith). Each Registration Statement required

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          hereunder shall contain (except if otherwise  directed by the Holders)
          the "Plan of  Distribution"  attached  hereto as Annex A. The  Company
          shall cause such Registration Statement to become effective and remain
          effective as provided  herein.  The Company shall use its commercially
          reasonable efforts to cause each Registration Statement to be declared
          effective  under the  Securities Act as promptly as possible after the
          filing  thereof,  but in any event not  later  than the  Effectiveness
          Date, and shall use its commercially  reasonable  efforts to keep such
          Registration Statement continuously effective under the Securities Act
          until  the  date  which  is  two  years   after  the  date  that  such
          Registration Statement is declared effective by the Commission or such
          earlier  date  when  all  Registrable   Securities   covered  by  such
          Registration  Statement  have been sold or may be sold without  volume
          restrictions  pursuant to Rule 144(k) as  determined by the counsel to
          the  Company  pursuant  to a written  opinion  letter to such  effect,
          addressed  and  acceptable  to the  Company's  transfer  agent and the
          affected Holders (the "Effectiveness Period").

               (b) If a  Registration  Statement  filed or  required to be filed
          hereunder is not declared effective by the Commission on or before the
          Effectiveness Date (any such failure or breach to be referred to as an
          "Event")  then in  addition  to any other  rights the Holders may have
          hereunder  or under  applicable  law: (x) on the seventh day after the
          date of such Event (the "Event  Date"),  the Company shall pay to each
          Holder an amount in cash or shares of the  Company's  Common Stock (at
          the Company's  option),  as  liquidated  damages and not as a penalty,
          equal to 1.5% of the  aggregate  purchase  price  paid by such  Holder
          pursuant to the Purchase Agreement for any Registrable Securities then
          held  by  such  Holder;  and  (y)  on  seventh  day  of  each  monthly
          anniversary of each such Event Date (if the applicable Event shall not
          have been cured by such date) until the applicable Event is cured, the
          Company  shall  pay to each  Holder an amount in cash or shares of the
          Company's  Common  Stock  (at the  Company's  option),  as  liquidated
          damages and not as a penalty,  equal to 1.5% of the aggregate purchase
          price paid by such Holder  pursuant to the Purchase  Agreement for any
          Registrable Securities then held by such Holder.

               (c) If during the Effectiveness Period, the number of Registrable
          Securities  at any time exceeds 100% of the number of shares of Common
          Stock then  registered in a Registration  Statement,  then the Company
          shall file as soon as reasonably  practicable but in any case prior to
          the  applicable  Filing Date,  an  additional  Registration  Statement
          covering  the  resale of by the  Holders  of not less than 100% of the
          number of such Registrable Securities.

     3. Registration Procedures

               In  connection  with  the  Company's   registration   obligations
          hereunder, the Company shall:

               (a) Not less than  three  Trading  Days  prior to the filing of a
          Registration  Statement or any related  Prospectus or any amendment or
          supplement  thereto,  the  Company  shall,  (i) furnish to the Holders
          copies of all such documents proposed to be filed (including documents
          incorporated  or  deemed  incorporated  by  reference  to  the  extent
          requested  by such  Person)  which  documents  will be  subject to the
          review of such

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          Holders,  and (ii)  cause its  officers  and  directors,  counsel  and
          independent  certified public accountants to respond to such inquiries
          as shall be necessary, in the reasonable opinion of respective counsel
          to  conduct a  reasonable  investigation  within  the  meaning  of the
          Securities Act. The Company shall not file a Registration Statement or
          any such Prospectus or any amendments or supplements  thereto to which
          the  Holders  of  a  majority  of  the  Registrable  Securities  shall
          reasonably object.

               (b) (i) Prepare  and file with the  Commission  such  amendments,
          including post-effective  amendments,  to a Registration Statement and
          the  Prospectus  used in  connection  therewith as may be necessary to
          keep  a  Registration  Statement  continuously  effective  as  to  the
          applicable  Registrable  Securities for the  Effectiveness  Period and
          prepare  and file with the  Commission  such  additional  Registration
          Statements  in order to register for resale under the  Securities  Act
          all of the Registrable  Securities;  (ii) cause the related Prospectus
          to be amended or supplemented by any required  Prospectus  supplement,
          and as so  supplemented  or amended to be filed  pursuant to Rule 424;
          (iii)  respond as promptly as  reasonably  possible,  and in any event
          within fifteen days, to any comments received from the Commission with
          respect to a Registration  Statement or any amendment  thereto and, as
          promptly as reasonably  possible,  upon  request,  provide the Holders
          true  and  complete  copies  of  all  correspondence  from  and to the
          Commission relating to such Registration Statement; and (iv) comply in
          all material  respects with the  provisions of the  Securities Act and
          the Exchange Act with respect to the  disposition  of all  Registrable
          Securities  covered by a Registration  Statement during the applicable
          period in accordance  with the intended  methods of disposition by the
          Holders thereof set forth in a Registration Statement as so amended or
          in such Prospectus as so supplemented.

               (c) Notify the Holders of  Registrable  Securities  to be sold as
          promptly as reasonably possible (and, in the case of (i)(A) below, not
          less than three  Trading Days prior to such filing) and (if  requested
          by any such Person) confirm such notice in writing promptly  following
          the day (i)(A)  when a  Prospectus  or any  Prospectus  supplement  or
          post-effective amendment to a Registration Statement is proposed to be
          filed; (B) when the Commission notifies the Company whether there will
          be a "review" of a Registration  Statement and whenever the Commission
          comments in writing on such Registration  Statement (the Company shall
          upon request  provide true and complete copies thereof and all written
          responses  thereto to each of the Holders);  and (C) with respect to a
          Registration Statement or any post-effective  amendment, when the same
          has become  effective;  (ii) of any request by the  Commission  or any
          other  Federal or state  governmental  authority  during the period of
          effectiveness   of  a   Registration   Statement  for   amendments  or
          supplements  to  a   Registration   Statement  or  Prospectus  or  for
          additional information; (iii) of the issuance by the Commission or any
          other  federal  or state  governmental  authority  of any  stop  order
          suspending the effectiveness of a Registration  Statement covering any
          or  all  of  the  Registrable  Securities  or  the  initiation  of any
          Proceedings  for that  purpose;  (iv) of the receipt by the Company of
          any notification  with respect to the suspension of the  qualification
          or exemption from  qualification of any of the Registrable  Securities
          for sale in any jurisdiction,  or the initiation or threatening of any
          Proceeding for such purpose; and (v) of the occurrence of any event or
          passage  of time that makes the  financial  statements  included  in a
          Registration   Statement  ineligible

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          for  inclusion  therein  or any  statement  made in such  Registration
          Statement or Prospectus or any document  incorporated  or deemed to be
          incorporated  therein by reference  untrue in any material  respect or
          that requires any revisions to such Registration Statement, Prospectus
          or other documents so that, in the case of a Registration Statement or
          the  Prospectus,  as the case may be, it will not  contain  any untrue
          statement  of a  material  fact or omit to  state  any  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.

               (d) Use its commercially reasonable efforts to avoid the issuance
          of, or, if issued,  obtain the withdrawal of (i) any order  suspending
          the effectiveness of a Registration  Statement, or (ii) any suspension
          of the qualification  (or exemption from  qualification) of any of the
          Registrable  Securities for sale in any jurisdiction,  at the earliest
          practicable moment.

               (e)  Furnish  to  each  Holder,  without  charge,  at  least  one
          conformed  copy of each  Registration  Statement  and  each  amendment
          thereto,  including financial statements and schedules,  all documents
          incorporated or deemed to be incorporated  therein by reference to the
          extent  reasonably  requested by such Person,  and all exhibits to the
          extent reasonably requested by such Person (including those previously
          furnished or incorporated  by reference)  promptly after the filing of
          such documents with the Commission.

               (f) Promptly  deliver to each  Holder,  without  charge,  as many
          copies  of the  Prospectus  or  Prospectuses  (including  each form of
          prospectus)  and each amendment or supplement  thereto as such Persons
          may reasonably request. The Company hereby consents to the use of such
          Prospectus  and each  amendment or  supplement  thereto by each of the
          selling  Holders  in  connection  with  the  offering  and sale of the
          Registrable Securities covered by such Prospectus and any amendment or
          supplement thereto.

               (g) Prior to any public offering of Registrable  Securities,  use
          its  commercially   reasonable  efforts  to  register  or  qualify  or
          cooperate with the selling Holders in connection with the registration
          or   qualification   (or   exemption   from   such   registration   or
          qualification) of such Registrable Securities for offer and sale under
          the  securities  or Blue Sky  laws of such  jurisdictions  within  the
          United States as any Holder  reasonably  requests in writing,  to keep
          each such  registration  or  qualification  (or  exemption  therefrom)
          effective during the Effectiveness  Period and to do any and all other
          acts or  things  reasonably  necessary  or  advisable  to  enable  the
          disposition  in  such  jurisdictions  of  the  Registrable  Securities
          covered by a Registration Statement;  provided, that the Company shall
          not  be  required  to  qualify   generally   to  do  business  in  any
          jurisdiction where it is not then so qualified, subject the Company to
          any  material  tax in any  such  jurisdiction  where it is not then so
          subject  or file a general  consent  to service of process in any such
          jurisdiction.

               (h)  Cooperate   with  the  Holders  to  facilitate   the  timely
          preparation  and  delivery of  certificates  representing  Registrable
          Securities to be delivered to a transferee  pursuant to a Registration
          Statement,  which  certificates shall be free, to the extent

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          permitted by the Purchase Agreement,  of all restrictive  legends, and
          to enable such Registrable  Securities to be in such denominations and
          registered in such names as any such Holders may request.

               (i) Upon the  occurrence  of any event  contemplated  by  Section
          3(c)(v), as promptly as reasonably  possible,  prepare a supplement or
          amendment,  including a  post-effective  amendment,  to a Registration
          Statement or a supplement  to the related  Prospectus  or any document
          incorporated  or deemed to be incorporated  therein by reference,  and
          file any other  required  document so that, as  thereafter  delivered,
          neither such  Registration  Statement nor such Prospectus will contain
          an 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 under which they were made, not
          misleading.

               (j)  Comply  with all  applicable  rules and  regulations  of the
          Commission.

               (k) The Company may require each selling Holder to furnish to the
          Company a  certified  statement  as to the  number of shares of Common
          Stock  beneficially  owned by such  Holder and,  if  requested  by the
          Commission, the controlling person thereof.

     4. Registration Expenses. All fees and expenses incident to the performance
     of or compliance  with this  Agreement by the Company shall be borne by the
     Company  whether or not any  Registrable  Securities are sold pursuant to a
     Registration Statement.  The fees and expenses referred to in the foregoing
     sentence shall include, without limitation, (i) all registration and filing
     fees (including,  without limitation, fees and expenses (A) with respect to
     filings  required  to be made with the  Trading  Market on which the Common
     Stock is then listed for trading,  and (B) in  compliance  with  applicable
     state  securities  or Blue Sky laws),  (ii) printing  expenses  (including,
     without  limitation,  expenses of  printing  certificates  for  Registrable
     Securities and of printing  prospectuses if the printing of prospectuses is
     reasonably  requested  by the  holders  of a  majority  of the  Registrable
     Securities  included  in  a  Registration   Statement),   (iii)  messenger,
     telephone and delivery expenses, (iv) fees and disbursements of counsel for
     the Company,  (v)  Securities  Act liability  insurance,  if the Company so
     desires such  insurance,  and (vi) fees and  expenses of all other  Persons
     retained  by  the  Company  in  connection  with  the  consummation  of the
     transactions contemplated by this Agreement. In addition, the Company shall
     be responsible for all of its internal expenses incurred in connection with
     the  consummation  of  the  transactions  contemplated  by  this  Agreement
     (including,  without limitation,  all salaries and expenses of its officers
     and employees  performing legal or accounting  duties),  the expense of any
     annual  audit and the fees and  expenses  incurred in  connection  with the
     listing  of the  Registrable  Securities  on  any  securities  exchange  as
     required hereunder.

     5. Indemnification

          (a) Indemnification by the Company. The Company shall, notwithstanding
     any termination of this Agreement, indemnify and hold harmless each Holder,
     the officers,  directors, agents and employees of each of them, each Person
     who  controls  any

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     such  Holder  (within the  meaning of Section 15 of the  Securities  Act or
     Section 20 of the Exchange  Act) and the  officers,  directors,  agents and
     employees of each such controlling  Person, to the fullest extent permitted
     by applicable  law, from and against any and all losses,  claims,  damages,
     liabilities,  costs (including,  without limitation,  reasonable attorneys'
     fees) and expenses (collectively, "Losses"), as incurred, arising out of or
     relating  to any  untrue or alleged  untrue  statement  of a material  fact
     contained  in a  Registration  Statement,  any  Prospectus  or any  form of
     prospectus or in any amendment or supplement  thereto or in any preliminary
     prospectus,  or  arising  out of or  relating  to any  omission  or alleged
     omission of a material fact  required to be stated  therein or necessary to
     make  the  statements  therein  (in the case of any  Prospectus  or form of
     prospectus or supplement thereto, in light of the circumstances under which
     they were  made) not  misleading,  except  to the  extent,  but only to the
     extent,  that (1) such untrue statements or omissions are based solely upon
     information  regarding  such Holder  furnished in writing to the Company by
     such  Holder  expressly  for  use  therein,  or to  the  extent  that  such
     information  relates to such  Holder or such  Holder's  proposed  method of
     distribution  of  Registrable  Securities  and was reviewed  and  expressly
     approved  in writing by such  Holder  expressly  for use in a  Registration
     Statement,  such  Prospectus or such form of Prospectus or in any amendment
     or  supplement  thereto (it being  understood  that the Holder has approved
     Annex A hereto for this  purpose) or (2) in the case of an occurrence of an
     event of the type specified in Section 3(c)(ii)-(v), the use by such Holder
     of an outdated or defective  Prospectus after the Company has notified such
     Holder in writing that the Prospectus is outdated or defective and prior to
     the receipt by such Holder of the Advice  contemplated in Section 6(c). The
     Company  shall notify the Holders  promptly of the  institution,  threat or
     assertion  of any  Proceeding  of which the Company is aware in  connection
     with the transactions contemplated by this Agreement.

          (b) Indemnification by Holders.  Each Holder shall,  severally and not
     jointly, indemnify and hold harmless the Company, its directors,  officers,
     agents and  employees,  each Person who  controls  the Company  (within the
     meaning of Section 15 of the  Securities Act and Section 20 of the Exchange
     Act), and the directors,  officers, agents or employees of such controlling
     Persons,  to the fullest  extent  permitted  by  applicable  law,  from and
     against all Losses,  as incurred,  arising out of or based solely upon: (x)
     such Holder's failure to comply with the prospectus  delivery  requirements
     of the Securities  Act or (y) any untrue or alleged  untrue  statement of a
     material fact contained in any Registration Statement,  any Prospectus,  or
     any form of prospectus, or in any amendment or supplement thereto or in any
     preliminary  prospectus,  or arising out of or relating to any  omission or
     alleged  omission  of a  material  fact  required  to be stated  therein or
     necessary to make the statements  therein not misleading (i) to the extent,
     but only to the extent, that such untrue statement or omission is contained
     in any  information  so  furnished in writing by such Holder to the Company
     specifically  for  inclusion  in  such   Registration   Statement  or  such
     Prospectus  or (ii) to the  extent  that  (1)  such  untrue  statements  or
     omissions are based upon  information  regarding  such Holder  furnished in
     writing to the Company by such Holder expressly for use therein,  or to the
     extent  that such  information  relates  to such  Holder  or such  Holder's
     proposed method of distribution of Registrable  Securities and was reviewed
     and  expressly  approved in writing by such Holder  expressly  for use in a
     Registration  Statement (it being  understood  that the Holder has approved
     Annex  A  hereto  for  this  purpose),  such  Prospectus  or  such  form of
     Prospectus or in any

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     amendment or  supplement  thereto or (2) in the case of an occurrence of an
     event of the type specified in Section 3(c)(ii)-(v), the use by such Holder
     of an outdated or defective  Prospectus after the Company has notified such
     Holder in writing that the Prospectus is outdated or defective and prior to
     the receipt by such Holder of the Advice  contemplated  in Section 6(c). In
     no event shall the liability of any selling Holder  hereunder be greater in
     amount than the dollar amount of the gross proceeds received by such Holder
     upon  the  sale  of  the  Registrable   Securities   giving  rise  to  such
     indemnification obligation.

          (c) Conduct of Indemnification Proceedings. If any Proceeding shall be
     brought or asserted against any Person entitled to indemnity  hereunder (an
     "Indemnified  Party"),  such  Indemnified  Party shall promptly  notify the
     Person from whom indemnity is sought (the "Indemnifying Party") in writing,
     and the  Indemnifying  Party  shall  have the right to assume  the  defense
     thereof, including the employment of counsel reasonably satisfactory to the
     Indemnified  Party and the  payment of all fees and  expenses  incurred  in
     connection  with  defense  thereof;  provided,  that  the  failure  of  any
     Indemnified  Party to give such notice  shall not relieve the  Indemnifying
     Party of its obligations or liabilities pursuant to this Agreement,  except
     (and only) to the extent that it shall be finally  determined by a court of
     competent  jurisdiction  (which  determination  is not subject to appeal or
     further  review) that such failure shall have  prejudiced the  Indemnifying
     Party.

          An Indemnified  Party shall have the right to employ separate  counsel
     in any such Proceeding and to participate in the defense  thereof,  but the
     fees  and  expenses  of  such  counsel  shall  be at the  expense  of  such
     Indemnified Party or Parties unless:  (1) the Indemnifying Party has agreed
     in writing to pay such fees and expenses;  (2) the Indemnifying Party shall
     have failed promptly to assume the defense of such Proceeding and to employ
     counsel  reasonably  satisfactory  to such  Indemnified  Party  in any such
     Proceeding;  or (3) the named parties to any such Proceeding (including any
     impleaded parties) include both such Indemnified Party and the Indemnifying
     Party, and such Indemnified Party shall have been advised by counsel that a
     conflict  of  interest  is  likely  to exist if the  same  counsel  were to
     represent such Indemnified Party and the Indemnifying Party (in which case,
     if such Indemnified  Party notifies the Indemnifying  Party in writing that
     it elects to employ  separate  counsel at the  expense of the  Indemnifying
     Party,  the  Indemnifying  Party  shall not have the  right to  assume  the
     defense  thereof  and the  reasonable  fees and  expenses  of one  separate
     counsel  shall  be  at  the  expense  of  the  Indemnifying   Party).   The
     Indemnifying  Party  shall not be  liable  for any  settlement  of any such
     Proceeding effected without its written consent, which consent shall not be
     unreasonably  withheld.  No  Indemnifying  Party  shall,  without the prior
     written  consent of the  Indemnified  Party,  effect any  settlement of any
     pending  Proceeding in respect of which any  Indemnified  Party is a party,
     unless  such  settlement   includes  an   unconditional   release  of  such
     Indemnified  Party from all liability on claims that are the subject matter
     of such Proceeding.

          All reasonable fees and expenses of the Indemnified  Party  (including
     reasonable  fees and  expenses to the extent  incurred in  connection  with
     investigating  or  preparing  to defend  such  Proceeding  in a manner  not
     inconsistent with this Section) shall be paid to the Indemnified  Party, as
     incurred,  within  ten  Trading  Days  of  written  notice  thereof  to the
     Indemnifying  Party;  provided,  that the Indemnified  Party shall promptly
     reimburse

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     the  Indemnifying  Party  for  that  portion  of  such  fees  and  expenses
     applicable to such actions for which such Indemnified Party is not entitled
     to indemnification hereunder,  determined based upon the relative faults of
     the parties.

          (d) Contribution. If a claim for indemnification under Section 5(a) or
     5(b) is unavailable to an Indemnified  Party (by reason of public policy or
     otherwise),  then each  Indemnifying  Party, in lieu of  indemnifying  such
     Indemnified  Party,  shall contribute to the amount paid or payable by such
     Indemnified  Party as a result of such  Losses,  in such  proportion  as is
     appropriate  to reflect the relative  fault of the  Indemnifying  Party and
     Indemnified  Party in connection with the actions,  statements or omissions
     that  resulted  in such  Losses  as well as any  other  relevant  equitable
     considerations.   The  relative  fault  of  such  Indemnifying   Party  and
     Indemnified  Party shall be determined by reference to, among other things,
     whether  any action in  question,  including  any untrue or alleged  untrue
     statement of a material fact or omission or alleged  omission of a material
     fact,  has been taken or made by, or relates to  information  supplied  by,
     such  Indemnifying  Party or Indemnified  Party, and the parties'  relative
     intent,  knowledge,  access to  information  and  opportunity to correct or
     prevent such action, statement or omission. The amount paid or payable by a
     party as a result of any Losses shall be deemed to include,  subject to the
     limitations  set forth in Section 5(c), any reasonable  attorneys' or other
     reasonable  fees or expenses  incurred by such party in connection with any
     Proceeding  to the extent such party would have been  indemnified  for such
     fees or expenses if the  indemnification  provided  for in this Section was
     available to such party in accordance with its terms.

          The parties  hereto  agree that it would not be just and  equitable if
     contribution  pursuant to this  Section  5(d) were  determined  by pro rata
     allocation  or by any other  method of  allocation  that does not take into
     account  the  equitable  considerations  referred  to  in  the  immediately
     preceding  paragraph.  Notwithstanding the provisions of this Section 5(d),
     no Holder shall be required to contribute,  in the aggregate, any amount in
     excess of the amount by which the proceeds actually received by such Holder
     from the  sale of the  Registrable  Securities  subject  to the  Proceeding
     exceeds  the amount of any  damages  that such  Holder has  otherwise  been
     required to pay by reason of such  untrue or alleged  untrue  statement  or
     omission or alleged omission, except in the case of fraud by such Holder.

          The indemnity and  contribution  agreements  contained in this Section
     are in addition to any liability that the Indemnifying  Parties may have to
     the Indemnified Parties.

          6. Miscellaneous

          (a) Remedies.  In the event of a breach by the Company or by a Holder,
     of any of their  obligations  under  this  Agreement,  each  Holder  or the
     Company,  as the case may be, in addition to being entitled to exercise all
     rights  granted  by law and under this  Agreement,  including  recovery  of
     damages,  will be entitled to specific performance of its rights under this
     Agreement.  The Company and each Holder agree that  monetary  damages would
     not provide  adequate  compensation  for any losses incurred by reason of a
     breach by it of any of the  provisions of this Agreement and hereby further
     agrees that, in

                                       9
<PAGE>

     the event of any action for specific performance in respect of such breach,
     it shall waive the defense that a remedy at law would be adequate.

          (b) Compliance.  Each Holder  covenants and agrees that it will comply
     with  the  prospectus  delivery  requirements  of  the  Securities  Act  as
     applicable  to  it in  connection  with  sales  of  Registrable  Securities
     pursuant to a Registration Statement.

          (c) Discontinued Disposition. Each Holder agrees by its acquisition of
     such Registrable Securities that, upon receipt of a notice from the Company
     of the occurrence of any event of the kind described in Section 3(c),  such
     Holder  will  forthwith   discontinue   disposition  of  such   Registrable
     Securities  under a Registration  Statement until such Holder's  receipt of
     the  copies of the  supplemented  Prospectus  and/or  amended  Registration
     Statement or until it is advised in writing  (the  "Advice") by the Company
     that the use of the applicable  Prospectus  may be resumed,  and, in either
     case, has received  copies of any additional or  supplemental  filings that
     are  incorporated  or  deemed  to be  incorporated  by  reference  in  such
     Prospectus or Registration  Statement.  The Company may provide appropriate
     stop orders to enforce the provisions of this paragraph.

          (d)  Amendments  and  Waivers.   The  provisions  of  this  Agreement,
     including the provisions of this sentence, may not be amended,  modified or
     supplemented,  and waivers or consents to  departures  from the  provisions
     hereof may not be given,  unless the same shall be in writing and signed by
     the  Company  and  Holders  holding  at least  50% of the then  outstanding
     Registrable Securities.

          (e) Notices. Any and all notices or other communications or deliveries
     required  or  permitted  to be provided  hereunder  shall be in writing and
     shall be deemed  given and  effective  on the  earliest  of (i) the date of
     transmission, if such notice or communication is delivered via facsimile at
     the facsimile  number  provided for below prior to 6:30 p.m. (New York City
     time)  on  a  Trading  Day,   (ii)  the  Trading  Day  after  the  date  of
     transmission, if such notice or communication is delivered via facsimile at
     the facsimile number provided for below later than 6:30 p.m. (New York City
     time) on any date and earlier than 11:59 p.m.  (New York City time) on such
     date,  (iii) the Trading  Day  following  the date of  mailing,  if sent by
     nationally  recognized  overnight  courier  service,  or (iv)  upon  actual
     receipt  by the party to whom  such  notice is  required  to be given.  The
     address  for  such  notices  and  communications  shall  be  delivered  and
     addressed as set forth in the Purchase Agreement.

          (f) Successors and Assigns.  This Agreement shall inure to the benefit
     of and be binding upon the successors and permitted  assigns of each of the
     parties  and  shall  inure to the  benefit  of each  Holder.  Except to its
     successors,  the Company may not assign its rights or obligations hereunder
     without the prior  written  consent of each Holder.  Each Holder may assign
     their  respective  rights  hereunder  in the manner  and to the  Persons as
     permitted under the Purchase Agreement.

          (g) Execution and Counterparts.  This Agreement may be executed in any
     number of  counterparts,  each of which when so executed shall be deemed to
     be an

                                       10
<PAGE>

     original and, all of which taken together shall constitute one and the same
     Agreement.  In the event  that any  signature  is  delivered  by  facsimile
     transmission, such signature shall create a valid binding obligation of the
     party  executing  (or on whose behalf such  signature is executed) the same
     with the same  force and  effect as if such  facsimile  signature  were the
     original thereof.

          (h)  Governing  Law.  All  questions   concerning  the   construction,
     validity,  enforcement  and  interpretation  of  this  Agreement  shall  be
     governed by and construed and enforced in accordance with the internal laws
     of the State of Delaware,  without regard to the principles of conflicts of
     law thereof.  Each party agrees that all legal  proceedings  concerning the
     interpretations,  enforcement and defense of the transactions  contemplated
     by this Agreement (whether brought against a party hereto or its respective
     affiliates,  directors, officers, shareholders,  employees or agents) shall
     be commenced  exclusively  in the state and federal  courts  sitting in the
     State of Delaware.  Each party  hereto  hereby  irrevocably  submits to the
     exclusive jurisdiction of the state and federal courts sitting in the State
     of Delaware for the adjudication of any dispute  hereunder or in connection
     herewith or with any transaction  contemplated  hereby or discussed  herein
     (including with respect to the  enforcement of the any of this  Agreement),
     and hereby irrevocably waives, and agrees not to assert in any suit, action
     or  proceeding,  any  claim  that  it is  not  personally  subject  to  the
     jurisdiction  of any such court,  that such suit,  action or  proceeding is
     improper.  Each party hereto hereby  irrevocably waives personal service of
     process and consents to process  being  served in any such suit,  action or
     proceeding by mailing a copy thereof via  registered  or certified  mail or
     overnight delivery (with evidence of delivery) to such party at the address
     in effect  for  notices  to it under this  Agreement  and agrees  that such
     service shall constitute good and sufficient  service of process and notice
     thereof.  Nothing  contained herein shall be deemed to limit in any way any
     right to serve  process in any manner  permitted by law.  Each party hereto
     hereby  irrevocably  waives,  to the fullest extent permitted by applicable
     law, any and all right to trial by jury in any legal proceeding arising out
     of or relating to this Agreement or the transactions  contemplated  hereby.
     If either  party  shall  commence  an action or  proceeding  to enforce any
     provisions of this Agreement,  then the prevailing  party in such action or
     proceeding  shall be reimbursed  by the other party for its attorneys  fees
     and other costs and expenses incurred with the  investigation,  preparation
     and prosecution of such action or proceeding.

          (i) Cumulative  Remedies.  The remedies provided herein are cumulative
     and not exclusive of any remedies provided by law.

          (j) Severability.  If any term, provision,  covenant or restriction of
     this Agreement is held by a court of competent  jurisdiction to be invalid,
     illegal,  void or  unenforceable,  the remainder of the terms,  provisions,
     covenants and  restrictions set forth herein shall remain in full force and
     effect and shall in no way be affected,  impaired or  invalidated,  and the
     parties hereto shall use their commercially  reasonable efforts to find and
     employ an alternative  means to achieve the same or substantially  the same
     result  as  that  contemplated  by  such  term,   provision,   covenant  or
     restriction.  It is hereby  stipulated  and declared to be the intention of
     the parties that they would have executed the

                                       11
<PAGE>

     remaining terms,  provisions,  covenants and restrictions without including
     any of such  that  may be  hereafter  declared  invalid,  illegal,  void or
     unenforceable.

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

          (l)  Independent  Nature of Purchasers'  Obligations  and Rights.  The
     obligations of each  Purchaser  hereunder is several and not joint with the
     obligations of any other  Purchaser  hereunder,  and no Purchaser  shall be
     responsible in any way for the  performance of the obligations of any other
     Purchaser hereunder.  Nothing contained herein or in any other agreement or
     document  delivered  at any closing,  and no action taken by any  Purchaser
     pursuant hereto or thereto, shall be deemed to constitute the Purchasers as
     a partnership, an association, a joint venture or any other kind of entity,
     or  create a  presumption  that the  Purchasers  are in any way  acting  in
     concert with respect to such obligations or the  transactions  contemplated
     by this Agreement.  Each Purchaser shall be entitled to protect and enforce
     its rights,  including  without  limitation  the rights arising out of this
     Agreement,  and it shall not be  necessary  for any other  Purchaser  to be
     joined as an additional party in any proceeding for such purpose.

                                    * * * * *

                                       12
<PAGE>


     IN WITNESS  WHEREOF,  the parties have  executed this  Registration  Rights
Agreement as of the date first written above.

                                CYTOGEN CORPORATION


                                By:/s/ Michael D. Becker
                                   --------------------------------
                                   Name:  Michael D. Becker
                                   Title: President and Chief Executive Officer

                     [PURCHASERS' SIGNATURE PAGES TO FOLLOW]


<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            STUART T. WEISBROD, IRA
                                            ------------------------------------
                                            Print Entity Name


                                            By: /s/ Stuart T. Weisbrod
                                               ---------------------------------
                                               Print Name: Stuart T. Weisbrod
                                               Print Title: Individual




<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                 Merlin BioMed Longterm Appreciation Fund, L.P.
                                 ----------------------------------------------
                                 Print Entity Name


                                 By: /s/ Norman Schleifer
                                    ---------------------------------
                                    Print Name: Norman Schleifer
                                    Print Title: CFO




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            STUART T. WEISBROD
                                            ------------------------------------
                                            Print Entity Name


                                            By: /s/ Stuart T. Weisbrod
                                               ---------------------------------
                                               Print Name: Stuart T. Weisbrod
                                               Print Title: Individual



<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            Merlin BioMed International Ltd.
                                            ------------------------------------
                                            Print Entity Name


                                            By: /s/ Norman Schleifer
                                               ---------------------------------
                                               Print Name: Norman Schleifer
                                               Print Title: CFO




<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            Merlin BioMed II L.P.
                                            ------------------------------------
                                            Print Entity Name


                                            By: /s/ Norman Schleifer
                                               ---------------------------------
                                               Print Name: Norman Schleifer
                                               Print Title: CFO




<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            Merlin BioMed Offshore Master Fund
                                            ------------------------------------
                                            Print Entity Name


                                            By: /s/ Norman Schleifer
                                               ---------------------------------
                                               Print Name: Norman Schleifer
                                               Print Title: CFO




<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            Merlin BioMed, L.P.
                                            ------------------------------------


                                            By: /s/ Norman Schleifer
                                               ---------------------------------
                                               Print Name: Norman Schleifer
                                               Print Title: CFO




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                           KNIGHTSBRIDGE POST VENTURE IV L.P.


                           By: /s/ Sven H. Borho
                              -------------------------------------------
                              Print Name: Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC


                           KNIGHTSBRIDGE INTEGRATED HOLDINGS, V, LP


                           By:/s/ Sven H. Borho
                              --------------------------------------------
                              Print Name:  Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC


                           KNIGHTSBRIDGE NETHERLANDS II, L.P.


                           By:/s/ Sven H. Borho
                              --------------------------------------------
                              Print Name:  Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC


                           KNIGHTSBRIDGE INTEGRATED HOLDINGS IV POST VENTURE, LP


                           By:/s/ Sven H. Borho
                              --------------------------------------------
                              Print Name:  Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC


                           KNIGHTSBRIDGE POST VENTURE III, LP


                           By:/s/ Sven H. Borho
                              --------------------------------------------
                              Print Name:  Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC


                           KNIGHTSBRIDGE NETHERLAND I LLP


                           By:/s/ Sven H. Borho
                              --------------------------------------------
                              Print Name:  Sven H. Borho
                              Print Title: Partner; OrbiMed Advisors LLC

<PAGE>


                                  KNIGHTSBRIDGE NETHERLANDS III - LP


                                  By:/s/ Sven H. Borho
                                     ---------------------------------
                                     Print Name:  Sven H. Borho
                                     Print Title: Partner; OrbiMed Advisors LLC



                                  KNIGHTSBRIDGE INTEGRATED HOLDINGS II LIMITED


                                  By:/s/ Sven H. Borho
                                     ---------------------------------
                                     Print Name:  Sven H. Borho
                                     Print Title: Partner; OrbiMed Advisors LLC



                                  KNIGHTSBRIDGE VENTURE CAPITAL IV L.P.


                                  By:/s/ Sven H. Borho
                                     ---------------------------------
                                     Print Name:  Sven H. Borho
                                     Print Title: Partner; OrbiMed Advisors LLC



                                  KNIGHTSBRIDGE VENTURE CAPITAL III LP


                                  By:/s/ Sven H. Borho
                                     ---------------------------------
                                     Print Name:  Sven H. Borho
                                     Print Title: Partner; OrbiMed Advisors LLC



                                 HFR SHC AGGRESSIVE FUND
                                 ------------------------------------


                                 By:/s/ Dora Hines
                                    ---------------------------------
                                    Print Name:  Dora Hines for & on
                                                 behalf of HFR Asset
                                                 Management, LLC as
                                                 attorney in fact
                                    Print Title:


<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]


                                            EXPRESSWAY PARTNERS, LTD.
                                            ------------------------------------


                                            By:/s/ Gerald Catenacci
                                               ---------------------------------
                                               Print Name:  Gerald Catenacci
                                               Print Title: Managing Member




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                            THRUWAY PARTNERS, LP
                                            ------------------------------------


                                            By:/s/ Gerald Catenacci
                                               ---------------------------------
                                               Print Name:  Gerald Catenacci
                                               Print Title: Managing Member




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                            HIGHWAY PARTNERS, LP
                                            ------------------------------------


                                            By:/s/ Gerald Catenacci
                                               ---------------------------------
                                               Print Name:  Gerald Catenacci
                                               Print Title: Managing Member




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   DOMAIN PUBLIC EQUITY PARTNERS, L.P.
                                   BY DOMAIN PUBLIC EQUITY ASSOCIATES, L.L.C.
                                   --------------------------------------------


                                   By:/s/ Nicole Vitullo
                                      ---------------------------------
                                      Print Name:  Nicole Vitullo
                                      Print Title: Managing Member




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   DELTA OPPORTUNITY FUND (Institutional), LLC
                                   --------------------------------------------

                                   Diaz & Altschul Management, LLC,
                                   Managing Member


                                   By:/s/ Christopher S. Mooney
                                      ---------------------------------
                                      Print Name:  Christopher S. Mooney
                                      Print Title: Chief Financial Officer




<PAGE>


                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                            THE TROUT GROUP LLC
                                            ------------------------------------


                                            By:/s/ Jonathan Fassberg
                                               ---------------------------------
                                               Print Name:  Jonathan Fassberg
                                               Print Title: President




<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   CLSP, L.P.
                                   ------------------------------------


                                   By:/s/ Jeffrey Casdin
                                      ---------------------------------
                                      Print Name:  Jeffrey Casdin
                                      Print Title: GP


<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   CLSP II, L.P.
                                   ------------------------------------


                                   By:/s/ Jeffrey Casdin
                                      ---------------------------------
                                      Print Name:  Jeffrey Casdin
                                      Print Title: GP


<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   CLSP SBS - I, L.P.
                                   ------------------------------------


                                   By:/s/ Jeffrey Casdin
                                      ---------------------------------
                                      Print Name:  Jeffrey Casdin
                                      Print Title: GP


<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   CLSP SBS - II, L.P.
                                   ------------------------------------


                                   By:/s/ Jeffrey Casdin
                                      ---------------------------------
                                      Print Name:  Jeffrey Casdin
                                      Print Title: GP

<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   CLSP OVERSEAS LTD.
                                   ------------------------------------


                                   By:/s/ Jeffrey Casdin
                                      ---------------------------------
                                      Print Name:  Jeffrey Casdin
                                      Print Title: Investment Manager


<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   MILLENCO L.P.
                                   ------------------------------------


                                   By:/s/ Robert Williams
                                      ---------------------------------
                                      Print Name:  Robert Williams
                                      Print Title: CFO

<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   VERTICAL VENTURES INVESTMENTS, LLC
                                   ------------------------------------


                                   By:/s/ Joshua Silverman
                                      ---------------------------------
                                      Print Name:  Joshua Silverman
                                      Print Title: Manager

<PAGE>



                       [PURCHASER'S SIGNATURE PAGE TO RRA]

                                   DELTA OPPORTUNITY FUND, LTD.
                                   ------------------------------------

                                   Diaz & Altschul Advisors, LLC,
                                   as Investment Advisor

                                   By:/s/ Christopher S. Mooney
                                      ---------------------------------
                                      Print Name:  Christopher S. Mooney
                                      Print Title: Chief Financian Officer

<PAGE>

                                                                         Annex A
                              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;

          -    settlement of 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.

     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.

     The Selling  Stockholders  may from time to time pledge or grant a security
interest in some or all of the shares of common stock 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 of 1933

<PAGE>

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 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 Selling  Stockholders  have informed the
Company  that it does not have  any  agreement  or  understanding,  directly  or
indirectly, with any person to distribute the Common Stock.

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