EXHIBIT 10.23
                                                            



[CYTOGEN CORPORATION LETTERHEAD]


June 9, 1997

Donald F. Crane, Jr.
11 Doubleday Lane
Ridgefield, CT 06877

Dear Mr. Crane:

CYTOGEN  Corporation  is pleased to offer you the position of Vice President and
General  Counsel at a  bi-weekly  salary of  $6,923.12  which is  annualized  at
$180,000, and effective on Monday, June 16, 1997, your employment date. You will
be reporting to the Chairman. This position is eligible for participation in the
Management  Group Bonus Plan.  While the amount of this bonus is determined each
year by the Board of  Directors,  the range for this is 0-25% of annual  salary.
You will also receive a relocation  package as outlined in the enclosed  CYTOGEN
Relocation Policy.

As a CYTOGEN employee, you are entitled to comprehensive  medical,  dental, life
AD&D, long-term disability, and travel and accident coverage.  Dependent medical
and dental coverage is also available. Employees contribute 20% towards the cost
of the premiums for medical and dental benefits. This amount is deducted through
payroll on a pre-tax basis. The total benefit package becomes  effective on your
first day of employment.

You have been  granted an option to  purchase  50,000  shares of CYTOGEN  Common
Stock pursuant to the CYTOGEN  Employee  Stock Option Plan which  describes this
aspect  of your  compensation.  A copy of the Plan  will be  provided  to you at
orientation.

The Vice  President  and General  Counsel  sits on the  Management  Committee of
CYTOGEN  Corporation  and as such is provided with an Executive  Secretary.  The
company  will  pay you a  monthly  car  allowance  of  $550.00  and will pay the
insurance and routine  maintenance  expenses for the car.  Management  Committee
members also receive  reimbursement of expenses incurred for financial  planning
and/or tax preparation in amounts up to $5,000.00 per year.

In the event of discharge  from duties,  for reasons other than just cause (e.g.
fraud,  criminal or willful misconduct),  you shall receive twelve months of pay
in accordance with past company practices.

Federal  law  requires  the  completion  of the  attached  form  (I-9)  and  our
examination of original  documentation from list A or from both list B and C. In
order to facilitate your employment,  you should complete Part 1 of the attached

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form and bring it with the necessary  supporting  documentation  to orientation.
You will also be required to sign CYTOGEN's  Secrecy Agreement and Photo Consent
Release forms and bring them with you on your first day of employment.

You will be required to schedule a  pre-employment  physical and should  contact
Rebecca  Bucci,  Manager of  Employment,  at  609-987-8289  to set up a mutually
agreeable time for your appointment. The pre-employment physical is conducted at
the Corporate Health Services of The Medical Center At Princeton. Directions are
attached. You must fast for twelve hours before the physical for the blood work.
This offer of  employment  is  contingent  on our receiving the results of these
tests prior to your employment date and is contingent upon your passing the drug
screening test.

Please indicate your acceptance of this offer by signing below and returning the
original  to my  attention.  This  offer will be  considered  null and void if a
signed  copy is not  returned  within  five  business  days of the  date of this
letter. We look forward to your joining us.

Sincerely,


/s/ Thomas J. McKearn                             /s/ Kim M. Moffa          
-----------------------------                     -------------------------
Thomas J. McKearn M.D., Ph.D.                     Kim M. Moffa
Chairman, President & CEO                         Director, Human Resources



ACCEPTED AND AGREED TO THIS 10th DAY OF JUNE, 1997

BY: /s/ Donald F. Crane, Jr.
    -------------------------
       Donald F. Crane, Jr.



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