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MEDIA/INVESTORS CONTACT:
Jonathan Fassberg
The Trout Group
(212) 477-9077 x16

              CYTOGEN REPORTS FIRST QUARTER 2005 FINANCIAL RESULTS

     Company Reaffirms Guidance of Record Revenues in Fiscal 2005, Full-Year
                  Operating Expense Guidance Revised Downward

PRINCETON,  N.J.,  (MAY 5,  2005)  --  Cytogen  Corporation  (Nasdaq:  CYTO),  a
product-driven   biopharmaceutical  company,  today  reported  its  consolidated
financial results for the quarter ended March 31, 2005.

FIRST QUARTER FINANCIAL HIGHLIGHTS
- ----------------------------------

o        Total product  revenues for the first quarter of 2005 were $4.0 million
         compared to $3.6 million in the first  quarter of 2004 and $3.7 million
         in  the  fourth  quarter  of  2004,  representing  10%  revenue  growth
         year-over-year and 6% sequential revenue growth from the fourth quarter
         of 2004.

o        Sales of QUADRAMET(R)  (samarium Sm-153 lexidronam injection) were $2.1
         million for the quarter  ended March 31, 2005  compared to $1.9 million
         for the same  period in 2004 and fourth  quarter of 2004,  representing
         11% revenue  growth  year-over-year  and 8% sequential  growth from the
         fourth quarter of 2004. Unit sales for the quarter ended March 31, 2005
         increased  8% from the  same  period  in 2004  and 9% from  the  fourth
         quarter of 2004.

o        Sales of PROSTASCINT(R) (capromab pendetide) kits were $1.9 million for
         the quarter  ended March 31, 2005 compared to $1.7 million for the same
         period  in 2004  and  $1.8  million  in the  fourth  quarter  of  2004,
         representing 10% revenue growth  year-over-year  and consistent  demand
         from the fourth quarter of 2004. Unit sales for the quarter ended March
         31, 2005  demonstrated  consistent  demand from the same period in 2004
         and from the fourth quarter of 2004.

o        Average  gross margin  improved to  39% for the quarter ended March 31,
         2005 compared to 33% for the same period in 2004.

o        Cytogen  reported  a net loss of $6.6  million,  or $0.43 per basic and
         diluted share in the first  quarter of 2005,  compared to $4.3 million,
         or $0.33 per basic and diluted share,  for the same period in 2004. The
         increase in net loss results primarily from the continued  expansion in
         Cytogen's sales force, which was completed in January 2005.

"We  remain  steadfast  in our  belief  that  QUADRAMET,  PROSTASCINT,  and  our
prostate-specific  membrane antigen, or PSMA,  development  pipeline are the key
drivers of our business model,  for which Cytogen has made solid progress during
the  first  quarter  of 2005,"  said  Michael  D.  Becker,  President  and Chief
Executive Officer.  "Whether measured by units or revenue,  we are encouraged by
the fact  that  QUADRAMET's  performance  in the first  quarter  of 2005 was the
highest in nearly three years, with the majority of demand occurring late in the
quarter as our expanded field presence began to have an impact. Additionally, we
are  pleased  with the  progress  made with  respect  to our  pipeline  of novel
therapies that target  prostate-specific  membrane antigen, or PSMA. We recently
announced a new clinical development  initiative for a proprietary PSMA antibody
designed to treat prostate and potentially  other cancers,  with plans to submit
an investigational  new drug (IND) application for this product candidate within
a year."



PRODUCT REVENUE
- ---------------

QUADRAMET

QUADRAMET, Cytogen's flagship product, is a fast-acting, long-lasting non-opioid
therapeutic  alternative  for the relief of pain due to metastatic  bone disease
arising from prostate, breast, multiple myeloma and other types of cancer. Sales
of QUADRAMET  were $2.1 million for the quarter ended March 31, 2005 compared to
$1.9 million for the same period in 2004.


                       QUADRAMET QUARTERLY REVENUE SUMMARY
                                ($'s in millions)

                       2004    2004    2004     2004     |   2005
                        Q1      Q2      Q3       Q4      |    Q1
                       ----    ----    ----     ----         ----

Product Sales          $1.9    $1.6    $1.9     $1.9     |   $2.1

"QUADRAMET's  demonstrated  ability to reduce pain and the need for opioid-based
treatments in cancer patients, along with its safety, simplicity, convenience of
administration,  and  cost-effectiveness  underscores our long-held  belief that
this unique product addresses a significant and unmet medical need," said Thomas
Lytle,  Cytogen's  Senior Vice  President of Sales and  Marketing.  "We are just
beginning  to  recognize  the  benefits of our  60-person-plus  core  commercial
organization  including  sales,  marketing,  and medical  affairs  functions and
targeted  programs  designed  to increase  awareness  of  QUADRAMET  in both key
physician and patient  audiences.  These  activities are expected to broaden the
use of QUADRAMET within its current palliative indication."

PROSTASCINT

Sales of  PROSTASCINT  kits  (for the  preparation  of  Indium  In-111  capromab
pendetide),  the first and only commercial monoclonal  antibody-based agent that
targets  PSMA to image the  extent  and  spread of  prostate  cancer,  were $1.9
million for the quarter  ended  March 31, 2005  compared to $1.7  million in the
same period of 2004.

                      PROSTASCINT QUARTERLY REVENUE SUMMARY
                                ($'s in millions)

                       2004    2004    2004     2004     |   2005
                        Q1      Q2      Q3       Q4      |    Q1
                       ----    ----    ----     ----         ----

Product Sales          $1.7    $2.3    $1.3     $1.8     |   $1.9

COSTS AND EXPENSES
- ------------------

Total operating expenses for the quarter ended March 31, 2005 were $10.7 million
compared to $7.9 million for the same period in 2004.

COST OF PRODUCT REVENUE

Cost of product revenue for both the quarters ended March 31, 2005 and March 31,
2004  were  $2.4  million  and  primarily   reflect  QUADRAMET  and  PROSTASCINT
manufacturing  costs,  royalties paid by Cytogen on the



Company's  product sales, and the amortization of the up-front payment to Berlex
to reacquire the marketing rights to QUADRAMET.

SG&A EXPENSES

Selling,  general and  administrative  expenses for the quarter  ended March 31,
2005 were $7.0 million compared to $3.9 million for the same period in 2004. The
increase in selling,  general and administrative expenses is primarily driven by
expanded   investment  for  the   commercial   support  of  both  QUADRAMET  and
PROSTASCINT,  including the continued expansion of the Company's sales force and
the implementation of new marketing initiatives.

R&D SPENDING

Internal research and development  expenses for the quarter ended March 31, 2005
were $739,000 compared to $804,000 for the same period in 2004.

External  research and development  expenses  reflect costs  associated with the
PSMA  Development  Company LLC  ("PDC"),  a joint  venture  between  Cytogen and
Progenics Pharmaceuticals,  Inc., for the development of in vivo immunotherapies
targeting  PSMA.  Cytogen's  share of the equity in the loss of PDC was $498,000
for the first quarter of 2005 compared to $809,000 for the same period in 2004.

INVENTORIES

Inventories  as of March 31, 2005 were $4.3 million  compared to $3.6 million as
of  December  31,  2004.  The  increase  in  inventories  was due  primarily  to
manufacturing  runs of PROSTASCINT.  In September  2004,  Cytogen entered into a
manufacturing agreement with Laureate Pharma, L.P. pursuant to which Laureate is
manufacturing  PROSTASCINT  for Cytogen in its Princeton,  New Jersey  facility.
Cytogen  believes  that the  agreement  will  provide  a  sufficient  supply  of
PROSTASCINT to satisfy  commercial  requirements for approximately the next four
years, based upon current sales levels.

CASH POSITION
- -------------

Cytogen's cash, cash equivalents and short-term  investments balance as of March
31, 2005 was $26.4 million compared to $35.8 million as of December 31, 2004.

FIRST QUARTER PRODUCT AND PIPELINE HIGHLIGHTS
- ---------------------------------------------

QUADRAMET

Four separate  studies are  evaluating  the safety and  preliminary  efficacy of
administering  QUADRAMET  in  combination  with a variety  of doses  and  dosing
regimens of taxane-based  chemotherapy  for the treatment of hormone  refractory
prostate  cancer.  Two  additional  studies are  evaluating  the  combination of
QUADRAMET with bisphosphonates,  one study in patients with multiple myeloma and
the  other  in  prostate  cancer.  These  Company-sponsored  studies  are  being
undertaken  not  only to  evaluate  potential  therapeutic  synergies  of  these
combinations  of  agents,  but also to  provide  clinical  data on the safety of
QUADRAMET  in  combination  with these other  agents  commonly  administered  to
patients with bone metastases in the approved indication for palliation of pain.

PSMA

Cytogen recently announced a new development  initiative for a targeted oncology
therapeutic  based on Cytogen's  proprietary 7E11 monoclonal  antibody  directed
against PSMA. This new therapeutic product



candidate utilizes DOTA-based bifunctional chelant technology to attach the beta
emitting radionuclide  lutetium-177 as a payload to the 7E11 antibody,  enabling
targeted  delivery  of this  cytotoxic  agent.  Cytogen  intends to develop  the
resulting  innovative molecule for the treatment of various cancers that express
the PSMA marker.  Pre-clinical studies are underway in anticipation of filing an
IND  application  in the first  quarter of 2006 for a Phase I study in  patients
with prostate cancer.

UPCOMING EVENTS
- ---------------

QUADRAMET

o        The  following two abstracts are scheduled to be presented or published
         at the American Society of Clinical Oncology (ASCO) annual meeting (May
         13-17, 2005):
            o  "Repeated  dose samarium 153  lexidronam  (QUADRAMET) in patients
               with  prostate  cancer  bone   metastases"  is  scheduled  to  be
               presented on Saturday, May 14 from 8:00 a.m. to 12:00 p.m. during
               the General Poster Session; and
            o  "Gemcitabine  radiosensitization  after  153Sm-EDTMP  (QUADRAMET)
               bone-seeking  radioisotope  therapy for  osteoblastic  lesions of
               osteosarcoma:   activity  and  principles"  is  scheduled  to  be
               presented on Monday,  May 16 from 8:00 a.m. to 12:00 p.m.  during
               the Poster Discussion Session.
o        The following four abstracts are scheduled to be presented or published
         at the Society of Nuclear  Medicine (SNM) annual meeting (June 18 - 22,
         2005):
            o  "Tumoricidal  effects of Sm-153  EDTMP  (QUADRAMET)  in  prostate
               cancer" is scheduled to be presented on Sunday, June 19 from 6:00
               p.m. to 6:45 p.m. during the Scientific Poster Session;
            o  "Treatment   of  painful  bony   metastases   with   samarium-153
               lexidronam (QUADRAMET): a review" is scheduled to be presented on
               Sunday, June 19 from 6:45 p.m. to 7:30 p.m. during the Scientific
               Poster Session;
            o  "153Sm-EDTMP  (QUADRAMET)  plus  chemotherapy in the treatment of
               bone metastases from lung cancer" is scheduled to be presented on
               Tuesday,  June  21  from  4:30  p.m.  to  5:15  p.m.  during  the
               Scientific Poster Session; and
            o  "A novel  study of the  measurement  of  samarium-153-EDTMP  bone
               uptake  rate and its  relationship  with  therapeutic  effect  in
               patients  with bone  metastases"  is scheduled to be presented on
               Tuesday,  June  21  from  4:30  p.m.  to  5:15  p.m.  during  the
               Scientific Poster Session.

PSMA

o        The following two abstracts are scheduled to be presented  or published
         at the ASCO annual meeting:
            o  "Novel  prime-boost   combinations  of  PSMA-based  vaccines  for
               prostate  cancer" is scheduled to be presented on Sunday,  May 15
               from 8:00 a.m. to 12:00 p.m.  during the General Poster  Session;
               and
            o  "Molecular  targeting  of  prostate  cancer with  cytotoxins  and
               radioisotopes linked to fully human monoclonal antibodies against
               prostate-specific  membrane antigen" is scheduled to be presented
               on Sunday, May 15 from 8:00 a.m. to 12:00 p.m. during the General
               Poster Session.
o        The following abstract is scheduled to be presented or published at the
         American  Urological  Association  (AUA)  annual  meeting (May 21 - 26,
         2005):
            o  "A negative indium-111-capromab  pendetide (PROSTASCINT) scan may
               still be useful" is scheduled to be presented on  Wednesday,  May
               25 from  3:30  p.m.  to 5:30  p.m.  during  a Podium  Session  on
               Uroradiology.
o        The following posters are scheduled to be presented or published at the
         American Brachytherapy Society (ABS) annual meeting (June 1 - 3, 2005):



            o  "Seven year  biochemical  disease free survival  rates  following
               permanent   prostate   brachytherapy   with  dose  escalation  to
               biological     tumor    volumes    (BTVs)     identified     with
               SPECT(PROSTASCINT)/CT  image fusion" is scheduled to be presented
               at the meeting; and
            o  "Rectal morbidity following permanent prostate brachytherapy with
               dose  escalation to biological  tumor volumes  (BTVs)  identified
               with  SPECT(PROSTASCINT)/CT  image  fusion"  is  scheduled  to be
               presented at the meeting.
o        The  following two abstracts are scheduled to be presented or published
         at the SNM annual meeting:
            o  "Scatter  correction  techniques for prostate SPECT imaging using
               indium 111 (PROSTASCINT)" is scheduled to be presented on Sunday,
               June 19 from 6:45 p.m. to 7:30 p.m. during the Scientific  Poster
               Session; and
            o  "Translation   of   SPECT/CT    (PROSTASCINT)   guided   prostate
               brachytherapy to a community setting from the university  setting
               with a case example of  histopathologic  correlation to the image
               set" is scheduled  to be presented on Tuesday,  June 21 from 4:30
               p.m. to 5:15 p.m. during the Scientific Poster Session.

"As  evidenced by more than a dozen  abstracts  scheduled  for  presentation  or
publication at major medical meetings during the current quarter,  we anticipate
that 2005 will be another  important  year for new data  related to our marketed
products and development  pipeline," said William Goeckeler,  Ph.D., Senior Vice
President  of  Operations  at Cytogen.  "We are  encouraged  by this support and
interest in our oncology  portfolio.  Through both ongoing and planned  clinical
development  programs,  we  continue  to make  progress  in  unlocking  the full
commercial potential of our products and pipeline."

FINANCIAL OUTLOOK FOR 2005
- --------------------------

This section  provides  forward-looking  information  about Cytogen's  financial
outlook  for 2005 based  upon our  current  operations.  The  disclosure  notice
paragraph regarding  forward-looking  statements at the end of this news release
is especially applicable to this section.

The Company reaffirms its previously  issued full-year 2005 financial  guidance,
with the exception of a downward revision in selling, general and administrative
expenses  to reflect  approximately  $5 million of certain  new  product  launch
expenses that the Company no longer expects to be recognized in 2005.

For the year ending December 31, 2005, the Company currently expects:

o        Total revenue of approximately $20 to $25 million;
o        Average gross margin of approximately 40% to 50%;
o        Revised  selling,  general   and  administrative   expenses    totaling
         approximately $25 to $30 million; and
o        Total  internal  and  external joint venture  research  and development
         expenses of approximately $10 to $15 million.

CONFERENCE CALL & WEBCAST INFORMATION
- -------------------------------------

Cytogen will  broadcast its  quarterly  investor  conference  call live over the
Internet  today,  May 5, 2005 at 9:00 a.m.  Eastern  Standard  Time. The dial-in
number for the U.S. is 1-800-659-1942 and the pass code number is 69636477.  The
dial-in number for  international  callers is  1-617-614-2710  and the pass code
number is 69636477.  This event can also be accessed by going to  Cytogen's  Web
site, www.cytogen.com,  and clicking on the "Investor Relations" link. A link to
the webcast is under the Calendar of Events  header.  The event will be archived
and  available  for replay  starting  approximately  one hour after the call and
continuing  for 7 days  thereafter.  The replay  dial-in  number for the U.S. is
888-286-8010 and the dial-in number for  international  callers is 617-801-6888.
The replay pass code number is 29606633.



NOTE:
- ----

QUADRAMET  is  indicated  for the  relief  of pain in  patients  with  confirmed
osteoblastic  metastatic  bone lesions that enhance on  radionuclide  bone scan.
This  press  release  describes  clinical  applications  that  differ  from that
reported in the QUADRAMET package insert.

PROSTASCINT  is  indicated  as a  diagnostic  imaging  agent in newly  diagnosed
patients with biopsy-proven  prostate cancer, thought to be clinically localized
after standard diagnostic  evaluation and who are thought to be at high risk for
pelvic  lymph node  metastases.  PROSTASCINT  is also  indicated as a diagnostic
imaging agent in post-prostatectomy patients with a rising PSA and a negative or
equivocal  standard  metastatic  evaluation  in whom  there  is a high  clinical
suspicion of occult metastatic  disease.  This press release describes  clinical
applications  and imaging  performance  that differs  from that  reported in the
PROSTASCINT package insert.

A copy of the full prescribing  information for QUADRAMET and PROSTASCINT may be
obtained in the U.S. from Cytogen  Corporation by calling toll free 800-833-3533
or by visiting the web site at www.cytogen.com,  which is not part of this press
release.

ABOUT CYTOGEN CORPORATION
- -------------------------

Founded  in 1980,  Cytogen  Corporation  of  Princeton,  NJ is a  product-driven
biopharmaceutical  company that develops and commercializes innovative molecules
that  can be used to  build  leading  franchises.  Cytogen's  marketed  products
include QUADRAMET(R)  (samarium Sm-153 lexidronam  injection) and PROSTASCINT(R)
(capromab pendetide) kit for the preparation of Indium In-111 capromab pendetide
in the United States.  Cytogen also has exclusive United States marketing rights
to COMBIDEX(R) (ferumoxtran-10) for all applications, and the exclusive right to
market and sell ferumoxytol  (previously Code 7228) for oncology applications in
the United  States.  Cytogen's  development  pipeline  consists of  therapeutics
targeting  prostate-specific membrane antigen (PSMA), a protein highly expressed
on the surface of prostate cancer cells and the  neovasculature of solid tumors.
Full  prescribing  information  for  the  Company's  products  is  available  at
www.cytogen.com or by calling 1-800-833-3533. For more information, please visit
the  Company's  website  at  www.cytogen.com,  which is not  part of this  press
release.


This press release  contains  certain  "forward-looking"  statements  within the
meaning of the Private Securities  Litigation Reform Act of 1995 and Section 21E
of the Securities Exchange Act of 1934, as amended.  All statements,  other than
statements of  historical  facts,  included in this press release  regarding our
strategy,  future operations,  financial  position,  future revenues,  projected
costs,  prospects,  plans  and  objectives  of  management  are  forward-looking
statements.  Such  forward-looking  statements  involve  a number  of risks  and
uncertainties  and investors are cautioned not to put any undue  reliance on any
forward-looking  statement.  There are a number of important  factors that could
cause  Cytogen's  results  to differ  materially  from those  indicated  by such
forward-looking  statements.  In particular,  Cytogen's business is subject to a
number of significant risks, which include,  but are not limited to: the risk of
obtaining  the  necessary  regulatory  approvals;  the risk of whether  products
result  from  development  activities;  the  risk of  shifts  in the  regulatory
environment  affecting  sales of Cytogen's  products such as  third-party  payor
reimbursement  issues;  the risk  associated  with  Cytogen's  dependence on its
partners for development of certain projects, as well as other factors expressed
from time to time in Cytogen's periodic filings with the Securities and Exchange
Commission  (the  "SEC").  As a result,  this  press  release  should be read in
conjunction with Cytogen's  periodic  filings with the SEC. The  forward-looking
statements  contained herein are made only as of the date of this press release,
and Cytogen  undertakes no obligation  to publicly  update such  forward-looking
statements to reflect subsequent events or circumstances.

                                       ###




                       CYTOGEN CORPORATION & SUBSIDIARIES
                (All amounts in thousands except per share data)
                                   (Unaudited)

                 CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS



                                                           THREE MONTHS ENDED
                                                                 MARCH 31,
                                                         -----------------------
                                                            2005          2004
                                                         ---------     ---------
                                                                 
Product Revenue:
     QUADRAMET                                           $  2,054      $  1,854
     PROSTASCINT                                            1,899         1,727
     Others                                                     -             1
                                                         --------      --------
             Total Product Revenue                          3,953         3,582


License and Contract Revenue                                   41            19
                                                         --------      --------
             Total Revenues                                 3,994         3,601
                                                         --------      --------

Operating Expenses:
     Cost of Product Revenue                                2,427         2,399
     Selling, General and Administrative                    7,024         3,891
     Research and Development                                 739           804
     Equity in Loss of Joint Venture                          498           809
                                                         --------      --------
             Total Operating Expenses                      10,688         7,903
                                                         --------      --------

Interest Income, Net                                          101            20
                                                         --------      --------
Net Loss                                                 $ (6,593)     $ (4,282)
                                                         ========      ========

Basic and Diluted Net Loss Per Share                     $  (0.43)     $  (0.33)
                                                         ========      ========

Weighted Average Common Shares Outstanding                 15,513        12,860
                                                         ========      ========





                           CONDENSED CONSOLIDATED BALANCE SHEETS



                                                               MARCH 31,   DECEMBER 31,
                                                                 2005          2004
                                                              ----------   ------------
                                                                      
Assets:
     Cash, Cash Equivalents and Short-Term Investments        $ 26,354      $ 35,825
     Accounts Receivable, Net                                    1,801         1,406
     Inventories                                                 4,255         3,623
     Property and Equipment, Net                                   851           787
     QUADRAMET License Fee, Net                                  6,850         7,024
     Other Assets                                                1,474         1,748
                                                              --------      --------
            Total Assets                                      $ 41,585      $ 50,413
                                                              ========      ========

Liabilities and Stockholders' Equity:
     Accounts Payable and Accrued Liabilities                 $  5,159      $  7,644
     Other Current Liabilities                                   2,690         2,692
     Long-Term Liabilities                                          42            47
     Stockholders' Equity                                       33,694        40,030
                                                              --------      --------
            Total Liabilities and Stockholders' Equity        $ 41,585      $ 50,413
                                                              ========      ========