Filed Pursuant to Rule 424(b)(2)
                                                              File No. 333-72226

                               CYTOGEN CORPORATION

               PROSPECTUS SUPPLEMENT NO. 1 DATED JANUARY 22, 2002
                    TO THE PROSPECTUS DATED OCTOBER 25, 2001

                                10,000,000 SHARES
                                       OF
                                  COMMON STOCK

     We are  selling  2,970,665  shares of  common  stock  with this  prospectus
supplement  and the  accompanying  prospectus at a purchase  price of $2.693 per
share, for aggregate proceeds of $8.0 million.

     You should  read this  prospectus  supplement  along with the  accompanying
prospectus.  These documents contain information you should consider when making
your investment decision.  You should rely only on the information  contained or
incorporated  by reference in this  prospectus  supplement and the  accompanying
prospectus.  We have not authorized anyone else to provide you with different or
additional  information.  The last  reported sale of our common stock on January
18,  2002 was $2.40 per  share.  Our common  stock is listed for  trading on the
Nasdaq National Market under the symbol "CYTO."

     This  prospectus   supplement  and  the  accompanying   prospectus  do  not
constitute an offer to sell or a solicitation  of an offer to buy any securities
other than the common stock offered hereby.  This prospectus  supplement and the
accompanying  prospectus do not constitute an offer to sell or a solicitation of
an  offer to buy our  common  stock  in any  circumstances  in which an offer or
solicitation is unlawful.

     Information in this prospectus  supplement and the accompanying  prospectus
may change after the date on the front of the  applicable  document.  You should
not interpret  the delivery of this  prospectus  supplement or the  accompanying
prospectus or the sale of the common stock as an indication  that there has been
no change in our affairs since such dates.

     Our  principal  executive  offices are  located at 600  College  Road East,
Princeton,   New  Jersey  08540.   Our  telephone   number  is  (609)  750-8200.

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

     INVESTING  IN OUR COMMON  STOCK  INVOLVES A HIGH DEGREE OF RISK.  SEE "RISK
FACTORS" BEGINNING ON PAGE 4 OF THE PROSPECTUS.

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

     NEITHER THE  SECURITIES AND EXCHANGE  COMMISSION  NOR ANY STATE  SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE  SECURITIES,  OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS  SUPPLEMENT.  ANY  REPRESENTATION TO THE
CONTRARY IS A CRIMINAL OFFENSE.

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

           THE DATE OF THIS PROSPECTUS SUPPLEMENT IS JANUARY 22, 2002.






                                     TABLE OF CONTENTS                   PAGE

Prospectus Supplement

Use Of Proceeds                                                           S-2
Plan Of Distribution                                                      S-2
Market For Our Common Stock                                               S-2
Information Incorporated By Reference                                     S-3
Forward-Looking Statements                                                S-3

Prospectus

About This Prospectus                                                      2
Cytogen Corporation                                                        3
Risk Factors                                                               4
Forward-Looking Statements                                                20
Use Of Proceeds                                                           21
Plan Of Distribution                                                      22
Legal Matters                                                             23
Experts                                                                   23
Where You Can Find More Information                                       23
Information Incorporated By Reference                                     23
Indemnification Of Directors And Officers                                 24

                                      S-1



                                 USE OF PROCEEDS

     We will use the net  proceeds  of this  offering  of our  common  stock for
general corporate purposes, including,  principally, working capital and capital
expenditures.

                              PLAN OF DISTRIBUTION

     We have not yet issued or sold any shares of our common  stock  pursuant to
the  prospectus  dated  October  25,  2001  which  is part  of our  Registration
Statement on Form S-3 (File No. 333-72226).

     We are  offering  2,970,665  shares  of our  common  stock to the  State of
Wisconsin  Investment Board pursuant to this prospectus  supplement.  The common
stock will be purchased at a price of $2.693 per share,  for aggregate  proceeds
to us of  $8,000,000.  Such  purchase  price is based upon a five  percent  (5%)
discount to market.

     We  issued  the  shares  of  common  stock  described  in  this  prospectus
supplement  directly to the State of Wisconsin  Investment Board in a negotiated
transaction  in which no party is  acting as an  underwriter  or  receiving  any
finder's or  placement  fees.  Prior to this  issuance,  the State of  Wisconsin
Investment  Board held,  and continues to hold,  the largest number of shares of
common stock of any of our stockholders.

     Upon sale under the  registration  statement that includes this  prospectus
supplement,  the securities  registered by such registration  statement and this
prospectus supplement will be freely tradable in the hands of persons other than
our affiliates.

     We agreed,  under the terms of a Share Purchase Agreement by and between us
and the  State of  Wisconsin  Investment  Board,  dated  January  18,  2002,  to
indemnify  and hold  harmless  the State of  Wisconsin  Investment  Board,  each
person, if any, who controls the State of Wisconsin  Investment Board within the
meaning  of  Section  15 of the  Securities  Act of 1933,  as  amended  and each
officer, director, employee and agent of the State of Wisconsin Investment Board
and of any such  controlling  person  against any and all  liabilities,  claims,
damages or expenses  whatsoever,  as incurred,  arising out of or resulting from
any breach or alleged breach or other violation of any representation, warranty,
covenant or  undertaking by us contained in such Share  Purchase  Agreement.  We
have  agreed  to  reimburse  the  State of  Wisconsin  Investment  Board for its
reasonable  legal and  other  expenses  (including  the  reasonable  cost of any
investigation and preparation, and including the reasonable fees and expenses of
counsel) incurred in connection therewith.

                           MARKET FOR OUR COMMON STOCK

     Our common stock is listed on the Nasdaq  National  Market under the symbol
"CYTO." On January 18, 2002,  the closing price of one share of our common stock
was $2.40. The common stock sold under this prospectus supplement will be listed
on the Nasdaq  National  Market after we notify the Nasdaq  National Market that
the shares have been issued. As of January 15, 2002, we had 79,793,241 shares of
common stock outstanding.

                                      S-2


                      INFORMATION INCORPORATED BY REFERENCE

     In addition  to those  documents  set forth  under the heading  Information
Incorporated By Reference in the accompanying prospectus, we also incorporate by
reference herein our proxy statement for our Annual Meeting of Stockholders held
on June 19, 2001.

                           FORWARD-LOOKING STATEMENTS

     This  prospectus   supplement  includes  or  incorporates   forward-looking
statements  within the meaning of Section 27A of the  Securities Act of 1933, as
amended and Section 21E of the Securities Exchange Act of 1934, as amended.  All
statements,  other than statements of historical facts, included or incorporated
in  this  prospectus  supplement  regarding  our  strategy,  future  operations,
financial  position,  future  revenues,  projected costs,  prospects,  plans and
objectives   of   management   are   forward-looking   statements.   The   words
"anticipates,"  "believes,"  "estimates,"  "expects," "intends," "may," "plans,"
"projects,"  "will,"  "would" and similar  expressions  are intended to identify
forward-looking statements,  although not all forward-looking statements contain
these  identifying  words. We cannot guarantee that we actually will achieve the
plans,  intentions or expectations  disclosed in our forward-looking  statements
and you should  not place  undue  reliance  on our  forward-looking  statements.
Actual results or events could differ materially from the plans,  intentions and
expectations  disclosed  in the  forward-looking  statements  we  make.  We have
included  important  factors  in the  cautionary  statements  included  with  or
incorporated in this prospectus supplement, particularly under the heading "Risk
Factors" in the  accompanying  prospectus,  that we believe  could cause  actual
results or events to differ materially from the forward-looking  statements that
we make. Our  forward-looking  statements do not reflect the potential impact of
any future acquisitions, mergers, dispositions, joint ventures or investments we
may  make.  We do not  assume  any  obligation  to  update  any  forward-looking
statements.

     You should not  unduly  rely on  forward-looking  statements  contained  or
incorporated  by  reference in this  prospectus  supplement.  Actual  results or
outcomes  may differ  materially  from those  predicted  in our  forward-looking
statements due to the risks and uncertainties inherent in our business.

                                      S-3