IMMUNOMEDICS INC
S-3, 1999-11-09
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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                                                     Registration No. 333-_____
                                                     Registration No. 333-699751
As filed with the Securities and Exchange Commission on November 9, 1999

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                   ----------


                                    FORM S-3

             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                                  ------------

                               IMMUNOMEDICS, INC.
             (Exact name of registrant as specified in its charter)

                Delaware                                  61-1009366
      (State or other jurisdiction of                 (I.R.S. Employer
       incorporation or organization)                  Identification No.)

                                300 American Road
                         Morris Plains, New Jersey 07950
                                 (973) 605-8200
                   (Address, including zip code, and telephone
                         number, including area code, of
                        registrant's principal executive
                                    offices)
                                  ------------

                             Dr. David M. Goldenberg
                      Chairman and Chief Executive Officer
                               Immunomedics, Inc.
                                300 American Road
                         Morris Plains, New Jersey 07950
                                 (973) 605-8200
 (Name, address, including zip code, and telephone number, including area code,
                              of agent for service)
                                  ------------

                          Copies of all communications,
                          including all communications
                              sent to the agent for
                           service, should be sent to:
                            Michael D. Schwamm, Esq.
                             Warshaw Burstein Cohen
                             Schlesinger & Kuh, LLP
                                555 Fifth Avenue
                            New York, New York 10017
                                 (212) 984-7700

Approximate  date of commencement  of proposed sale to the public:  From time to
time after the effective date of this Registration Statement.

If the only securities  being registered on this Form are being offered pursuant
to dividend or interest reinvestment plans, please check the following box: [ ]

If any of the  securities  being  registered on this Form are to be offered on a
delayed or continuous  basis  pursuant to Rule 415 under the  Securities  Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box: [x]

If this Form is filed to register additional securities for an offering pursuant
to Rule 462(b) under the Securities Act, please check the following box and list
the  Securities  Act  registration  statement  number of the  earlier  effective
registration statement for the same offering. [ ]

- --------
1     As permitted by Rule 429 under the Securities Act of 1933, the  prospectus
      contained  in  this  registration  statement  also relates to Registration
      Statement on Form S-3, registration no. 333-69975.

<PAGE>

If this Form is a  post-effective  amendment filed pursuant to Rule 462(c) under
the  Securities  Act,  check  the  following  box and  list the  Securities  Act
registration  statement number of the earlier effective  registration  statement
for the same offering. [ ]

If  delivery  of  the  prospectus  is  expected to be made pursuant to Rule 434,
please check the following box:  [ ]

<TABLE>
<CAPTION>

====================================================================================================================================
                                                      CALCULATION OF REGISTRATION FEE
- ------------------------------------------------------------------------------------------------------------------------------------
<S>                             <C>                        <C>                        <C>                      <C>
   Title of Each Class of       Amount of Shares to be      Proposed Maximum          Proposed Maximum              Amount of
Securities to be Registered(1)       Registered(2)         Offering Price Per             Aggregate            Registration Fee(4)
                                                               Share(3)(4)            Offering Price(3)(4)
- ------------------------------------------------------------------------------------------------------------------------------------
Common Stock, $.01 par
   value per share                     9,878,463                $1.1875                  $11,730,675                 $3,261
- ------------------------------------------------------------------------------------------------------------------------------------
Common Stock, $.01 par                 7,950,069                   ---                        --                       ---
   value per share
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)      We originally registered  on  Form S-3  (Registration No. 333-69975) an
         aggregate of 10,000,000 shares of common stock issuable upon conversion
         of  shares  of  our Series F  Preferred Stock.   The Series F Preferred
         Stock was originally issued in December 1998.  Through the date of this
         registration statement,  232.5 shares  of Series F Preferred Stock have
         been converted into 2,049,931 shares of common stock. Accordingly, this
         registration  statement  is  intended to cover an  additional 9,878,463
         shares  of common  stock in  addition to the 7,950,069 shares of common
         stock  previously  registered,   all of  which  may  be  issuable  upon
         conversion of the remaining 1,017.5 shares of Series F Preferred Stock.

(2)      Consists  of  shares  of  common  stock  issuable  upon  conversion  of
         outstanding shares of Series F Preferred Stock.

(3)      Relates to 9,878,463  shares of common stock which may be issuable upon
         conversion of shares of the Series F Preferred Stock that have not been
         previously  registered.  As  set  forth  in  note  (1),  we  previously
         registered pursuant to the original  registration  statement 10,000,000
         shares of common stock issuable upon conversion of the shares of Series
         F Preferred Stock, and paid the associated  registration fee of $8,601.
         Of these shares, 7,950,069 shares of common stock have yet to be resold
         pursuant to the original registration statement.

(4)      Pursuant to Rule 457(c),  the proposed maximum offering price per share
         and proposed maximum  aggregate  offering price have been calculated on
         the basis of the  average of the high and low sale prices of our common
         stock as reported on The Nasdaq National Market on November 3, 1999.

The Registrant hereby amends this  Registration  Statement on such date or dates
as may be necessary to delay its effective date until the Registrant  shall file
a further amendment which specifically  states that this Registration  Statement
shall  thereafter  become  effective  in  accordance  with  Section  8(a) of the
Securities  Act of  1933  or  until  the  Registration  Statement  shall  become
effective on such date as the  Commission,  acting pursuant to Section 8(a), may
determine.

<PAGE>

The  information in this Prospectus is subject to completion and may be changed.
The selling  stockholders  may not sell these  securities until the registration
statement  filed with the  Securities  and  Exchange  Commission  (of which this
Prospectus  is a part) is  effective.  This  Prospectus  is not an offer to sell
these securities, and is not soliciting an offer to buy these securities, in any
state where such offer or sale is not permitted


PROSPECTUS


                               IMMUNOMEDICS, INC.

                        17,828,532 Shares of Common Stock



THE ISSUER

Immunomedics.  Inc.
300 American Road
Morris Plains, New Jersey 07950
(973) 605-8200


THE SELLING STOCKHOLDERS

The selling  stockholders  are offering to sell shares of common stock that they
may acquire  upon  conversion  of shares of our Series F  Convertible  Preferred
Stock  that we  issued to them on  December  9, 1998  pursuant  to a  Securities
Purchase  Agreement.  This prospectus covers an additional  9,878,463 shares  of
common stock in addition to the 7,950,069  shares of common stock  included in a
prior  prospectus.  Additional  information  concerning  our agreement  with the
selling  stockholders  is set forth under the caption  "Immunomedics  - December
1998 Financing."


TRADING SYMBOL

Nasdaq National Market -  "IMMU"


THE OFFERING

The selling  stockholders  may sell shares of our common stock from time to time
on the Nasdaq  National  Market at the  prevailing  market  price or in private,
negotiated  transactions.  The shares will be sold at prices  determined  by the
selling  stockholders.  We will not  receive any part of the  proceeds  from the
sale.  We are paying the expenses in  connection  with the  registration  of the
shares with the SEC. The selling stockholders may be deemed to be "underwriters"
within the meaning of the Securities  Act in connection  with the sale of shares
that they may receive upon conversion of the Series F Stock.


A purchase of shares  involves a high degree of risk. You should purchase shares
only if you can afford a complete loss of your  investment.  See "Risk  Factors"
beginning on page 3.


Neither  the  Securities  and  Exchange  Commission  nor  any  state  securities
commission  has approved or disapproved  these  securities or determined if this
prospectus  is truthful or  complete.  Any  representation  to the contrary is a
criminal offense.


                                 _________, 1999


<PAGE>



                                Table of Contents

Risk Factors...................................................................4
         We Have a History of Operating Losses and May Never Become
           Profitable..........................................................4
         We May Not Be Able to Successfully Develop a Market for Our Approved
           Products............................................................4
         We May Not Receive Approval to Sell LeukoScan in the United States
           in a Timely Manner..................................................4
         We May Not Be Able to Bring to Market the Products We Are Currently
           Developing..........................................................4
         If We Do Not Obtain Additional Capital, We May Be Required to Curtail
           Our Operations......................................................5
         Our Limited Marketing and Sales Experience and Capability Could Impact
           Our Ability to Successfully Sell Our Current Products...............5
         We May Have to Rely on Partners to Help Us Market and Sell Our
           Products Under Development..........................................5
         We Could Be Temporarily Unable to Sell Our Products If Our Agreements
           with our Distributors Were Terminated...............................5
         We Could Be Temporarily Unable to Sell Our Products If Our Agreement
           with our End Stage Manufacturer Was Terminated......................5
         Our Internal Manufacturing Capability May Limit What We Can Sell......5
         We May Be Unable to Continue to Use Mouse Fluids for Future Products
           Which Could Require Us to Make Expensive and Time Consuming Changes
           to Our Products in Development......................................6
         Our Product Development Is Dependent Upon Our Continued Relationship
           with The Center for Molecular Medicine and Immunology...............6
         Certain Potential Conflicts of Interest Exist with The Center for
           Molecular Medicine and Immunology Which Could Affect Our
           Operations..........................................................6
         We May Not Be Able to Obtain Government Regulatory Approval in a
           Timely Manner to Market and Sell Our Products.......................6
         We Must Maintain Our Manufacturing Facilities in Accordance With
           Government Regulatory Requirements..................................7
         Changes to Health Care Reimbursement Could Adversely Affect Our
           Operations..........................................................7
         The Loss of Key Employees Could Adversely Affect our Operations.......7
         We Face Substantial Competition in the Biotechnology Field and
           May Not Be Able to Successfully Compete.............................7
         Our Products May Be Rendered Obsolete By Rapid Technological Change...8
         If We Are Unable to Protect Our Intellectual Property Rights, We
           Could Lose Our Competitive Advantage................................8
         Our Products May Infringe Third Party Intellectual Property Rights....8
         Our Operations Could Suffer If We Are Unsuccessful in Our Pending
           Infringement Claims Concerning Our CEA Antibodies...................8
         Product Liability Claims in Excess of the Amount of Our Insurance
           Would Adversely Affect Our Financial Condition......................8
         Our Principal Stockholder Can Influence Most Matters Requiring
           Approval By Our Stockholders........................................9
         If We Are Required to Redeem the Series F Stock or Make Penalty
           Payments, Our Financial Condition Would Be Adversely Affected.......9
         Stockholders May Experience Substantial Dilution From the
           Conversion of the Series F Stock....................................9
         Short Selling of Our Common Stock Could Further Depress the Market
           Price for Our Common Stock..........................................9
         Resales of Shares Held By Our Directors and Executive Officers May
           Lower the Market Price of Our Common Stock..........................9
         Our Stock Price Has Been Volatile....................................10
         Potential Loss of Our Nasdaq Listing Could Make it More Difficult
           to Sell our Shares and Affect Our Liquidity........................10
         Stockholders Could Be Adversely Affected By Our Anti-Takeover
           Provisions.........................................................10
         Our Operations Could Be Affected By Year 2000 Issues.................10
         No Expectation that We Will Pay Dividends............................11
         Special Note Regarding Forward-Looking Statements....................11

Where You Can Find More Information...........................................11

Immunomedics..................................................................12

                                        2
<PAGE>

         Description of Our Business..........................................12
         December 1998 Financing..............................................14

Use of Proceeds...............................................................17

Selling Stockholders..........................................................18

Plan of Distribution..........................................................20
         Manner of Sales; Broker-Dealer Compensation..........................20
         Filing of a Post-Effective Amendment In Certain Instances............21
         Certain Persons May Be Deemed to Be Underwriters.....................21
         Regulation M.........................................................21

Legal Matters.................................................................22

Experts  .....................................................................22











You should rely on the information incorporated by reference or provided in this
prospectus or any supplement.  We have not authorized anyone to provide you with
different  information.  You  should  not assume  that the  information  in this
prospectus  or any  supplement is accurate as of any date other than the date on
the front of such  document.  We are not  making  an offer of our  shares in any
state where the offer is not permitted.


                                        3
<PAGE>


                                  Risk Factors

         Investing  in our common  stock  involves a high  degree of risk.  As a
result,  you should be able to sustain a complete  loss of your  investment.  In
addition  to the other  information  in this  prospectus,  you should  carefully
consider the following factors before purchasing any of our common stock.

We Have a History of Operating Losses and May Never Become Profitable

         We have had  significant  operating  losses since our formation in 1982
and have not earned a profit since our  inception.  These  operating  losses and
failure to be profitable have been due mainly to the significant amount of money
that we have had to spend on research and  development.  As of June 30, 1999, we
had an accumulated deficit of approximately  $99,100,000.  We expect to continue
to experience  operating  losses until such time, if at all, that we are able to
generate sufficient revenues from sales of CEA-Scan(R),  LeukoScan(R) and/or our
other potential products.

We May Not Be Able to Successfully Develop a Market for Our Approved Products

         CEA-Scan and LeukoScan  are the only products  which we are licensed to
market and sell. To date,  we have received only limited  revenues from the sale
of these  products.  We cannot  assure  you that  these  products  or any of our
proposed products will achieve market acceptance or generate significant sales.

We May Not Receive Approval to Sell LeukoScan in the United States in a Timely
Manner

         We have  not yet  received  approval  from the FDA to  market  and sell
LeukoScan in the United States and cannot  assure you as to when, if ever,  that
we will obtain  approval.  In addition,  the FDA could impose  conditions on its
approval,  which could  significantly  affect the  commercial  viability  of the
product  or could  require us to  undertake  significant  additional  studies or
otherwise expend additional  significant funds. If we do not receive approval to
market and sell  LeukoScan in the United States in the near future or if the FDA
imposes  significant  conditions or  restrictions,  our business and  operations
could be significantly and adversely affected.

We May Not Be Able to Bring to Market the Products We Are Currently Developing

         Before any of our  products  that we are  currently  developing  can be
marketed and sold, we must undertake  substantial research and development.  All
new products face a high degree of uncertainty, including the following:

*        We may not receive regulatory approval to perform human clinical trials
         for the  products  we  currently  have  planned  or we may be unable to
         successfully complete our ongoing clinical trials.

*        The results from  preclinical  studies and  clinical  trials may not be
         indicative of results that will be obtained in later-stage testing.

*        We may be unable to timely recruit a sufficient  number of patients for
         our clinical trials. Delays in planned patient enrollment may result in
         increased costs and delays.

*        We may be unable to obtain approval from the FDA and comparable foreign
         authorities  because we are unable to  demonstrate  that the product is
         safe and  effective  for the  intended  use,  or  obtaining  regulatory
         approval may take  significantly  more time and cost significantly more
         money than we currently anticipate.

*        We may discover that the product has  undesirable  or  unintended  side
         effects  or  other   characteristics   that  make  it   impossible   or
         impracticable  for us to  continue  development  or which may limit the
         product's commercial use.

*        We do not expect that any new product  which is  currently  in research
         and  development  will be  commercially  available for at least several
         years.

*        We may be unable to produce the product in commercial quantities at
         reasonable cost.


                                        4
<PAGE>


*        We may be unable  to  successfully  market  the  product  or to find an
         appropriate  corporate  partner,  if  necessary,  to  assist  us in the
         marketing of the product.

*        The product may not gain satisfactory market acceptance.

*        The product may be superceded by another product commercialized for the
         same indication or may infringe  patents issued to others,  which would
         prevent us from marketing and selling the product.

         If  we  are  unable  to  continue  to  develop  products  that  we  can
successfully market, our business, financial condition and results of operations
will be significantly and adversely affected.

If We Do Not Obtain Additional Capital, We May Be Required to Curtail Our
Operations

         Without a significant increase in product revenues or other infusion of
capital  during our  current  fiscal year which ends June 30,  2000,  we will be
required to significantly reduce our operating expenses, including the amount of
resources  devoted to  marketing  and sales,  product  development  and clinical
trials,  which  could have a  significant  and  adverse  effect on us. We cannot
assure you that any  additional  financing  will be available to us at all or on
terms we find  acceptable  or that the  terms of any  financing  will not  cause
substantial dilution to our existing stockholders.

Our Limited Marketing and Sales Experience and Capability Could Impact Our
Ability to Successfully Sell Our Current Products

         We are  relying,  in  substantial  part,  on our own limited  sales and
marketing  organization to market  CEA-Scan and LeukoScan.  We cannot assure you
that we can  successfully  maintain and continue to build our sales force. If we
are unable to continue to build and  maintain  our sales  force,  our  financial
condition and operating results may be significantly and adversely affected.

We May Have to Rely on Partners to Help Us Market and Sell Our Products Under
Development

         The marketing and sale of our proposed  products may be dependent  upon
our entering into  arrangements  with corporate  partners.  We cannot assure you
that we  will  be  successful  in  forming  these  relationships  or that  these
relationships, even if formed, will be successful.

We Could Be Temporarily Unable to Sell Our Products If Our Agreements with our
Distributors Were Terminated

         We  currently  do not have the  resources  to  internally  develop  and
maintain the operating  procedures  required by the FDA and  comparable  foreign
regulatory  authorities to oversee distribution of our products. As a result, we
have entered into  arrangements  with third parties to perform this function for
the foreseeable future. If these agreements are terminated,  we will be required
to enter into arrangements with other government approved third parties in order
to be  able to  distribute  our  products.  We will be  unable  to  continue  to
distribute  our products until an acceptable  alternative  is identified.  If we
were even only temporarily unable to distribute our products, our business could
be significantly and adversely effected.

We Could Be Temporarily Unable to Sell Our Products If Our Agreement with our
End Stage Manufacturer Was Terminated

         We rely on a single third party to perform certain  end-stage  portions
of the  manufacturing  process for CEA-Scan and LeukoScan which we are unable or
do not have the  resources  to  perform.  If this  third  party  were to  become
unavailable,  we would be unable to complete the manufacturing  process until we
entered into an agreement with another  qualified  entity. We cannot assure that
we will be able to  negotiate  an  agreement  with  another  entity  on terms we
consider  acceptable,  if at all. Even if we were able to do so, any substantial
delay in our  ability  to  manufacture  our  products  could  significantly  and
adversely affect our operations.

Our Internal Manufacturing Capability May Limit What We Can Sell


                                        5
<PAGE>


         If demand for our approved product increases  significantly,  we cannot
assure you that we will continue to have the capacity to manufacture  commercial
quantities successfully.  In addition, if any of our other products are approved
for  marketing  and sale, we cannot assure you that we will continue to have the
capacity and expertise to manufacture commercial quantities of multiple products
successfully or with acceptable profit margins. If we were even only temporarily
unable to manufacture  sufficient quantities of our products to meet demand, our
business could be significantly and adversely effected.


We May Be Unable to Continue to Use Mouse Fluids for Future Products Which Could
Require Us to Make Expensive and Time Consuming Changes to Our Products in
Development

         CEA-Scan  and  certain of our other  imaging  agents are  derived  from
ascites fluid produced in mice. Regulatory authorities,  particularly in Europe,
have  expressed  concerns  about  the use of mice  fluid for the  production  of
monoclonal  antibodies.  We cannot assure you that regulatory  authorities  will
agree that our quality control  procedures will be adequate for future products.
While we are  continuing  our  development  efforts  to  produce  certain of our
monoclonal  antibodies  using cell culture methods,  this process  constitutes a
substantial  production  change,  which will  require  additional  manufacturing
equipment and new  regulatory  approval.  We cannot assure you that we will have
the resources to acquire the additional manufacturing equipment and resources or
that we will receive the required  regulatory  approval on a timely basis, if at
all.  We also  have  contracted  with a third  party  for  the  development  and
production  of certain  humanized  antibodies,  but we cannot  assure that these
efforts will be successful.

Our Product Development Is Dependent Upon Our Continued Relationship with The
Center for Molecular Medicine and Immunology

         The Center for  Molecular  Medicine and  Immunology,  a  not-for-profit
cancer research center,  performs pilot and pre-clinical trials in product areas
of importance to us. CMMI also conducts basic  research and patient  evaluations
in a number  of areas of  potential  interest  to us.  If CMMI were no longer to
provide these  services,  we would have to make  alternative  arrangements  with
third parties which could  significantly  delay and increase expenses associated
with pre-clinical testing and initial clinical trials.

Certain Potential Conflicts of Interest Exist with The Center for Molecular
Medicine and Immunology Which Could Affect Our Operations

         Dr. David M. Goldenberg,  our Chairman and Chief Executive Officer,  is
the  founder,  President  and a member of the  Board of  Trustees  of CMMI.  Dr.
Goldenberg  devotes  more of his time working for CMMI than for us. In addition,
other key personnel  currently have  responsibilities  both to CMMI and us. As a
result,  the potential for conflict of interest  exists and disputes could arise
over the allocation of research projects and ownership of intellectual  property
rights.

We May Not Be Able to Obtain Government Regulatory Approval in a Timely Manner
to Market and Sell Our Products

         Regulation by governmental authorities in the United States and foreign
countries  is a  significant  factor in the  manufacture  and  marketing  of our
presently marketed and proposed products as well as our research and development
activities.  All of our proposed  products will require  regulatory  approval by
governmental  agencies prior to commercialization  and our products must undergo
rigorous   preclinical  and  clinical  testing  and  other  premarket   approval
procedures by the FDA and comparable  foreign  authorities.  In addition,  since
certain of our potential  products involve the application of new  technologies,
regulatory  approvals  may take longer  than for  products  produced  using more
conventional  methods.  Once we begin  clinical  trials for a new  diagnostic or
therapeutic  product,  it may  take  five to ten  years or more to  receive  the
required  regulatory  approval to commercialize that product and begin to market
it to the  public.  Various  federal  and,  in some cases,  state  statutes  and
regulations  also  govern or  influence  the  manufacturing,  safety,  labeling,
storage,  record keeping and marketing of these products. The lengthy process of
seeking these approvals,  and the subsequent compliance with applicable statutes
and regulations,  will require us to expend substantial resources. If we fail to
obtain  or  are  otherwise   substantially  delayed  in  obtaining,   regulatory
approvals,  our business and  operations  could be  significantly  and adversely
affected.


                                        6
<PAGE>


         In  responding  to  a  new  drug  application,  or a  biologic  license
application,  government  regulators  may  grant  marketing  approvals,  request
additional  information  or  further  research,  or deny the  application  if it
determines  that  the  application  does not  satisfy  its  regulatory  approval
criteria.  Approvals  may not be granted  on a timely  basis,  if at all,  or if
granted  may not cover all the  clinical  indications  for which we are  seeking
approval  or may  contain  significant  limitations  in the  form  of  warnings,
precautions or contraindications with respect to conditions of use.

Our Business Involves the Use of Hazardous Materials

         In  addition to laws and  regulations  enforced by the FDA, we are also
subject to regulation under various other foreign,  federal, state or local laws
and  regulations.  Our research and  development  involve the  controlled use of
hazardous materials,  chemicals,  viruses and various radioactive compounds. The
risk of  accidental  contamination  or injury  from  these  materials  cannot be
completely  eliminated.  If an accident occurs,  we could be held liable for any
damages that result and any liability could exceed our resources.

We Must Maintain Our Manufacturing Facilities in Accordance With Government
Regulatory Requirements

         Our  facilities  are subject to  inspection  by the FDA and  comparable
foreign  authorities.  A separate  license is sometimes  required for commercial
manufacture  of any product.  Failure to maintain  these licenses or to meet the
regulatory  inspection  criteria would result in disruption to our manufacturing
processes  and could have a significant  and adverse  effect on our business and
operations.

Changes to Health Care Reimbursement Could Adversely Affect Our Operations

         Our ability to successfully  commercialize  our products will depend in
part on the  extent  to which  reimbursement  for the cost of our  products  and
related  treatment  will be  available  from  government  health  administration
authorities, private health insurers and other organizations.  These third-party
payers are increasingly  challenging the price of medical products and services.
Several proposals have been made that may lead to a government-directed national
health  care  system.  Adoption  of this  type of  system  could  further  limit
reimbursement  for  medical  products,  and we cannot  assure you that  adequate
third-party  coverage  will be available  to enable us to maintain  price levels
sufficient  to  realize  an  appropriate  return on our  investment  in  product
development.  In addition, we also cannot assure you that the U.S. government or
foreign  governments  will not implement a system of price controls.  Any system
might  significantly  and  adversely  affect our ability to market our  products
profitably.

The Loss of Key Employees Could Adversely Affect our Operations

         As a small  biotechnology  company,  we are heavily  dependent upon the
talents  of  Dr.  Goldenberg  and  certain  key  scientific  personnel.  If  Dr.
Goldenberg or any of our other key personnel  leave our employ,  our  operations
could be significantly and adversely affected. In addition, from time to time we
have a need to expand our management and scientific  personnel.  Competition for
qualified  personnel  in the  biotechnology  and  pharmaceutical  industries  is
intense and we cannot assure you that we will be  successful in our  recruitment
efforts.  If we are  unable  to  retain  or,  when  needed,  attract  additional
qualified  personnel,  our operations also could be significantly  and adversely
affected.

We Face Substantial Competition in the Biotechnology Field and May Not Be Able
to Successfully Compete

         The biotechnology  industry is highly competitive,  particularly in the
area of cancer diagnostic and therapeutic  products.  We are likely to encounter
significant  competition  with respect to our  existing  products as well as our
products  currently  under  development.  A number of companies,  including IDEC
Pharmaceuticals,  Genentech,  SmithKline Beecham,  Nycomed Amersham, and Coulter
Pharmaceutical,  are engaged in the  biotechnology  field, and in particular the
development  of  cancer  diagnostic  and  therapeutic  products.  Many of  these
companies  have  significantly   greater  financial,   technical  and  marketing
resources  than  us.  In  addition,  many  of  these  companies  may  have  more
established positions in the pharmaceutical  industry and may be better equipped
than us to develop, refine and market their products.


                                        7
<PAGE>


         We also expect to face increasing  competition  from  universities  and
other  non-profit  research  organizations.   These  institutions  carry  out  a
significant  amount of research and  development in the field of  antibody-based
technology.  These  institutions  are  becoming  increasingly  more aware of the
commercial  value of their  findings and more active in seeking patent and other
proprietary rights, as well as licensing revenues.

Our Products May Be Rendered Obsolete By Rapid Technological Change

         We are  pursuing an area of product  development  in which there is the
potential for extensive technological innovations in relatively short periods of
time. We cannot assure you that our  competitors  will not succeed in developing
products that are safer or more effective than our products. Rapid technological
change or developments  by others may result in our current  products as well as
those in development becoming noncompetitive or obsolete.

If We Are Unable to Protect Our Intellectual Property Rights, We Could Lose Our
Competitive Advantage

         Our  commercial  success is highly  dependent  upon  patents  and other
proprietary  rights  that we own or license.  We cannot  assure you that our key
patents  will  not be  invalidated  or  will  provide  us  protection  that  has
commercial  significance.  Litigation  may be  necessary  to protect  our patent
positions,  which could be costly and time consuming.  If any of our key patents
that we own or license are invalidated,  our business may be  significantly  and
adversely  affected.  In addition,  other  companies may  independently  develop
similar  trade  secrets  or  know-how  or obtain  access  to our trade  secrets,
know-how or  proprietary  technology,  which could  significantly  and adversely
affect our business.

Our Products May Infringe Third Party Intellectual Property Rights

         Other companies may have filed  applications  for, or have been issued,
patents  and  obtained  other  proprietary  rights  to  technology  which may be
potentially useful to us. Since we do not have the resources to maintain a staff
whose primary  function is to  investigate  the level of protection  afforded to
third  parties on devices and  components  which we use in our  products,  it is
possible that a third party could  successfully claim that our products infringe
on their intellectual  property rights. If this were to occur, we may be subject
to substantial damages, and we may not be able to obtain appropriate licenses at
a cost we could  afford and we may not have the ability to timely  redesign  our
products.  If we are  required  to pay  damages  or are  unable to obtain  these
rights, our business could be significantly and adversely  affected.  Even if we
are successful in defeating any alleged  infringement  claims,  litigation could
result in a substantial diversion of managerial time and resources,  which could
be better and more fruitfully utilized on other activities.

Our Operations Could Suffer If We Are Unsuccessful in Our Pending Infringement
Claims Concerning Our CEA Antibodies

         We are involved in certain litigation with F.  Hoffmann-LaRoche and its
affiliates concerning the validity our European patents covering the antibody we
use in our CEA-Scan cancer imaging product and our  CEA-Cide(TM)  cancer therapy
product,  as well as the use of highly specific anti-CEA antibodies for a number
of other uses. We have claimed that they have infringed our patent and they have
counterclaimed seeking to nullify the patents that were issued. If we receive an
unfavorable outcome in any of these matters, our business could be significantly
and adversely affected.

Product Liability Claims in Excess of the Amount of Our Insurance Would
Adversely Affect Our Financial Condition

         The  clinical  testing,  marketing  and  manufacturing  of our products
necessarily  involve  the risk of product  liability.  While we  currently  have
product  liability  insurance,  we cannot  assure that we will be able to obtain
insurance in the future at an acceptable  cost, if at all. If we cannot maintain
our existing or comparable liability  insurance,  our ability to test clinically
and market our products may be significantly impaired.  Moreover, the amount and
scope  of our  insurance  coverage  or  indemnification  arrangements  with  any
distributor or other third party upon which we rely may be inadequate to protect
us in the event of a successful  product liability claim. Any claim in excess of
the amount any insurance we then had could  significantly  and adversely  affect
our financial condition.

                                        8
<PAGE>


Our Principal Stockholder Can Influence Most Matters Requiring Approval By Our
Stockholders

         As of  November  9,  1999,  Dr.  Goldenberg,  our  Chairman  and  Chief
Executive  Officer,  controlled the right to vote over  approximately 32% of our
common stock.  As a result of this voting  power,  Dr.  Goldenberg  may have the
ability to determine the election of all of our  directors,  direct our policies
and control the outcome of substantially  all matters which may be put to a vote
of our stockholders.

If We Are Required to Redeem the Series F Stock or Make Penalty Payments, Our
Financial Condition Would Be Adversely Affected

         As  discussed  below  in the  section  "Immunomedics  -  December  1998
Financing" upon the occurrence of certain  circumstances,  we may be required to
redeem the Series F Stock or pay significant penalties. These penalties could be
as much as 15% per year of the stated  value of the Series F Stock.  We also may
be required to reduce the conversion  price of the Series F Stock.  In addition,
if the registration statement of which this prospectus is a part is not declared
effective by the SEC on or before  December 11, 1999,  we may be required to pay
the  holders  of the  Series  F Stock  penalties  equal  to $5 per day for  each
outstanding share of Series F Stock, retroactive to when our original prospectus
first became  insufficient  to cover all the shares  issuable upon conversion of
the Series F Stock. These penalties could be significant.  If we are required to
redeem  the  Series F Stock or make the  penalty  payments,  we may not have the
financial ability to make these payments. Even if we have the financial ability,
these payments could  significantly and adversely affect our financial condition
and deplete our cash resources.

Stockholders May Experience Substantial Dilution From the Conversion of the
Series F Stock

         Because the conversion price of the Series F Stock is not fixed, we may
be required to issue to the holders of the Series F Stock a  significant  number
of shares of our common stock.  The conversion price generally will be the lower
of $2.50 and the average  closing bid price of our common  stock over the lowest
15 days during the 45-day period immediately prior to the applicable  conversion
date.  As of November 9, 1999,  the  conversion  price would have been $1.18 per
share and we would have been  required to issue  approximately  8,914,266 of our
common stock had the holders converted all of their remaining outstanding Series
F Stock on this date.  If our stock  price  decreases,  we would be  required to
issue an  increased  number of shares and the  greater the decline in the market
price,  the  greater  the  number of shares we would be  required  to issue upon
conversion of our Series F Stock.

         Given that the  conversion  price is based on the average of the lowest
closing price during a specified  period,  the market price for our common stock
may be significantly greater than the conversion price for the Series F Stock in
effect at the time of conversion.  In this case, the conversion of a significant
number  of  Series  F  Stock  into  common   stock   during  that  period  would
significantly  dilute the percentage  ownership  interest of our existing common
stockholders.

Short Selling of Our Common Stock Could Further Depress the Market Price for Our
Common Stock

         Subject to the limitations  described below in "Immunomedics - December
1998  Financing,"  the holders of the Series F Stock are permitted to sell short
our common stock;  that is sell shares of common stock that they do not own. The
selling  stockholders could then convert their Series F Stock and use the shares
of common stock  received  upon  conversion to cover their short  position.  The
perception  that the selling  stockholders  may sell short our common  stock may
cause  others to sell their  shares as well.  An increase in the sales volume of
our common  stock,  whether  short sales or not and whether the sales are by the
selling  stockholders or others, could potentially cause the market price of our
common stock to decline further.  Since the Series F Stock became convertible in
June 1999, the monthly reported short position in our common stock had increased
250% from 575,000 at June 15, 1999 to its high of  2,103,000  at  September  15,
1999 and as of October 15, 1999, the short position was 1,740,322.

Resales of Shares Held By Our Directors and Executive Officers May Lower the
Market Price of Our Common Stock

         As of November  9, 1999,  we had a total of 39,938,021 shares of common
stock outstanding,


                                        9
<PAGE>


7,130,272 of which were held by our  directors  and  executive  officers.  These
shares may only be resold in limited  quantities and only within the limitations
imposed  by Rule 144 under the  Securities  Act.  The mere  prospect  that these
shares may be publicly resold could lower the market price for our common stock.

Our Stock Price Has Been Volatile

         We believe  that a variety of factors  have caused the market  price of
our  common  stock to  fluctuate  substantially,  and that it will  continue  to
fluctuate in the future. These factors include:

*        actual or anticipated fluctuations in our operating results;

*        the status of our products in development;

*        new products or technical innovations by us or by our existing or
           potential competitors;

*        the formation or termination of our corporate alliances and
           distribution arrangements;

*        prolonged periods of regulatory review of new products or new uses for
           existing products;

*        determinations regarding our patent applications and those of others;

*        trading strategies occurring in the market place with respect to our
           common stock; and

*        general market conditions and other factors unrelated to us or outside
           our control.

Potential Loss of Our Nasdaq Listing Could Make it More Difficult to Sell our
Shares and Affect Our Liquidity

          If the bid price of our  common  stock  were to fall  below  $1.00 per
share,  if we were to have less than  $4,000,000  in net tangible  assets (total
assets less total liabilities and goodwill), or if the value of our common stock
held by our stockholders  (other than our directors and executive officers) were
to be less than  $5,000,000,  our common stock could be delisted from The Nasdaq
Stock Market.  If our common stock were  delisted  from Nasdaq,  trading if any,
would thereafter be conducted in the over-the-counter market. This would make it
more difficult for an investor to dispose of, or to obtain  accurate  quotations
for, our common  stock.  Additionally,  it may become more  difficult  for us to
raise funds through the sale of our securities.  Finally, as discussed elsewhere
in this prospectus,  a delisting of our common stock would also give the holders
of the Series F Stock certain redemption rights.

Stockholders Could Be Adversely Affected By Our Anti-Takeover Provisions

         Our board of directors has the  authority,  without any further vote by
our stockholders,  to issue up to 10,000,000 shares of preferred stock in one or
more series and to determine the designations, powers, preferences and relative,
participating,  optional or other rights  thereof,  including the dividend rate,
whether dividends are cumulative,  conversion rights,  voting rights, rights and
terms of redemption,  redemption price and liquidation  preference.  Issuance of
preferred  stock could have the effect of delaying,  deterring  or  preventing a
change in control of our company,  or could impose various  procedural and other
requirements  that could make it more  difficult for holders of our common stock
to effect certain corporate actions,  including the ability to replace incumbent
directors  and to  accomplish  transactions  opposed by the  incumbent  board of
directors.  The rights of the  holders of our common  stock would be subject to,
and may be  adversely  affected  by, the rights of the holders of any  preferred
stock that may be issued in the future.

Our Operations Could Be Affected By Year 2000 Issues

         We have  completed  a review of our  business  systems,  including  our
computer systems and manufacturing equipment, and have sent written inquiries to
our customers,  distributors and vendors as to their progress in identifying and
addressing  problems that their systems may face in correctly  interpreting  and
processing date information as the year 2000 approaches and is reached. We could
encounter  problems with supplier  and/or revenue sources which could affect us.
We cannot accurately


                                       10
<PAGE>


predict the occurrence or outcome of any these problems, nor can we estimate the
dollar  amount of these  problems.  In  addition,  we cannot  assure  you that a
failure by a third party to ensure year 2000 compliance  will not  significantly
and adversely effect us.

No Expectation that We Will Pay Dividends

         We  have  never  paid  any  dividends  on our  common  stock.  For  the
foreseeable  future,  we expect to  retain  earnings,  if any,  to  finance  the
expansion and development of our business.  Any future payment of dividends will
be within  the  discretion  of our Board of  Directors  and will  depend  upon a
variety of factors, including our earnings, capital requirements,  and operating
and financial condition.  In addition, we are required to obtain the approval of
the holders of the Series F Stock prior to the payment of any  dividends  on our
common stock.

Special Note Regarding Forward-Looking Statements

         We have made  statements  in this  prospectus,  and in the documents we
incorporate  by  reference,  that are  "forward-looking  statements"  within the
meaning of the Securities Act and the Securities  Exchange Act.  Sometimes these
statements contain words like "may," "believe," "expect,"  "continue," "intend,"
"anticipate" or other similar words.  These  statements  could involve known and
unknown risks,  uncertainties and other factors that might  significantly  alter
the actual results suggested by the statements.  In other words, our performance
might be quite different from what the  forward-looking  statements  imply.  The
following  factors,  as well as those  discussed  above in this  "Risk  Factors"
section and in the documents which we incorporate by reference,  could cause our
performance to differ from the implied results:

         *        inherent uncertainties accompanying the marketing of CEA-Scan
                  and LeukoScan.

         *        inherent uncertainties involving new product development and
                  marketing.

         *        inability to obtain capital for continued product development
                  and commercialization.

         *        actions of regulatory authorities concerning product approval.

         *        actions of government and private organizations concerning
                  reimbursement of medical expenses.

         *        impact of competitive products and pricing.

         *        results of clinical trials.

         *        loss of key employees.

         *        changes in general economic and business conditions.

         *        changes in industry trends.

         We have no obligation  to release  publicly the result of any revisions
to any of our  "forward-looking  statements" to reflect events or  circumstances
that occur after the date of this  prospectus  or to reflect the  occurrence  of
other unanticipated events.


                       Where You Can Find More Information

         We  publicly  file  annual,   quarterly  and  current  reports,   proxy
statements and other  documents with the SEC. You may read and copy any of these
documents at the SEC's public reference rooms in Washington, D.C., New York City
and Chicago.  Please call the SEC at 1-800-SEC-0330  for further  information on
the  public   reference   rooms.   The  SEC  maintains  a  Internet  website  at
http://www.sec.gov where our publicly filed documents may be obtained.

         This prospectus is part of a registration statement filed with the SEC.
Our registration statement


                                       11
<PAGE>


contains more information than this prospectus regarding us and our common stock
and includes supplemental  exhibits and schedules.  You can obtain a copy of the
registration  statement  from the SEC at the  address  listed  above or from its
Internet website.

         The SEC allows us to  "incorporate  by reference"  into this prospectus
the  information we file with it. This means that we are deemed to be disclosing
such information to you by referring you to those documents. This information is
important and should be reviewed.  The information  incorporated by reference is
considered to be part of this  prospectus,  and later  information  that we file
with the SEC will  automatically  update and supercede the  information  in this
prospectus.

         We incorporate by reference into this  prospectus the documents  listed
below and any future filings we make with the SEC under Sections  13(a),  13(c),
14 or 15(d) of the Securities Exchange Act:

         *        Annual Report on Form 10-K for the fiscal year ended June 30,
                  1999;

         *        Proxy Statement, dated October 18, 1999, with respect to our
                  1999 annual meeting of
                  stockholders; and

         *        Description  of the common  stock  contained  in Item 1 of our
                  Registration Statement on Form 8-A, dated May 7, 1984.

         You may request a copy of these  filings,  at no cost, by contacting us
at the following address:

                  Immunomedics, Inc.
                  300 American Road
                  Morris Plains, New Jersey 07950
                  (973) 605-8200
                  Attention: Investor Relations


                                  Immunomedics

Description of Our Business

         We are a biopharmaceutical  company,  which develops,  manufactures and
markets  products for the detection and treatment of cancers and other diseases.
These  products,  which are based on our  monoclonal  antibody  technology,  are
designed to deliver  radioisotopes,  chemotherapeutic  agents,  toxins,  dyes or
other substances to a specific disease site or organ system.

         We have received  approval from the respective  regulatory  agencies in
the United States,  the 15 member  countries of the European  Union,  Canada and
certain other countries to market and sell CEA-Scan  (arcitumomab),  our imaging
product for the detection of recurrent and/or metastatic colorectal cancer.

         We  also  have   received   approval  to  market  and  sell   LeukoScan
(sulesomab),  our imaging  product for detection and diagnosis of  osteomyelitis
(bone  infection) in long bones and in diabetic foot ulcer  patients,  in the 15
member  countries of the European Union.  We have filed an application  with the
FDA in the U.S. and the comparable  regulatory  agency in Canada for approval to
market  LeukoScan for imaging of infection in  osteomyelitis  as well as for the
imaging  of  infection  in  acute,  atypical  appendicitis.  The  review  of the
LeukoScan  submission  to the FDA  continues to progress.  As part of the review
process,  we are in discussions with the FDA to address their comments regarding
the adequacy of our data to support final approval for these indications. We are
confident  that we can  bring  these  discussions  with  the  FDA to  successful
closure.  In the meantime,  we are  continuing to implement our plans for market
introduction,  and are  working  diligently  on  preparation  to bring  this new
product to the U.S. market place.

         Marketing, Sales and Distribution

         CEA-Scan  is  marketed  and sold in the U.S.  directly  by our  limited
internal sales force,  who are focused on new customers in major medical centers
that we hope will become colorectal cancer


                                       12
<PAGE>


"Centers of Excellence." Our skilled nuclear medicine technicians work with this
sales force and provide  technical  support  directly to our customers.  We have
entered  into  a   distribution   arrangement   in  the  U.S.  with   Integrated
Commercialization  Solutions,  a division  of Bergen  Brunswig  Corporation,  to
provide product support services including  customer service,  order management,
distribution,  invoicing  and  collection.  We also have  agreement  with Syncor
International,  the world's leading  provider of radiopharmacy  services,  under
which Syncor  makes  CEA-Scan  available  to its  hospital  and clinic  accounts
throughout the U.S., supported by our sales and technical support specialists.

         Our European  operations,  headquartered in Hillegom,  The Netherlands,
include  European  management,   sales  and  marketing,   customer  service  and
invoicing,   collection  and  other  administrative   functions.  We  also  have
established  sales  representation  in most major European  markets.  We service
other markets  through the appointment of local  distributors  who provide sales
and  marketing  support  as  well  as  local  product  distribution.  We have an
agreement with Eli Lilly Deutschland GmbH to package and distribute our products
throughout the 15 member countries of the European Union and other countries.

         Imaging Products

         Our imaging  products  involve  injecting a patient with a radioisotope
attached to an  antibody  fragment.  An antibody is a protein  that can find and
attach  itself to a specific  substance  called an antigen.  These  antigens are
present  on tumor  cells,  white  blood  cells that  accumulate  at the sites of
infections,   and  other  disease  entities.   A  radioisotope   attached  to  a
disease-targeting  antibody  is  delivered  to a  disease  site for  imaging.  A
standard  nuclear  medicine  imaging  camera is then used to detect and  display
radioisotope concentrations at various sites of disease.

         The antibody fragment in CEA-Scan is directed against  carcinoembryonic
antigen  (CEA),  which is abundant at the site of  virtually  all cancers of the
colon or rectum,  whether they are primary tumors or which have spread. CEA also
is  associated  with many other  cancers.  We are  conducting  phase IV clinical
trials to evaluate the product following repeated  administration.  We also have
been  performing  clinical  trials  using  CEA-Scan  for imaging lung cancer and
breast  cancer.  We are  discussing  the results of these  clinical  trials with
European regulatory authorities to determine whether these data will support the
submission  of  applications  for  marketing  approval.   In  addition,  we  are
continuing our efforts in developing cancer detection applications with CEA-Scan
utilizing  hand-held  radiation-detecting  probes for use in  colorectal  cancer
surgery.

         LeukoScan is a monoclonal antibody fragment, which seeks out, and binds
to white blood cells (granulocytes)  associated with a potentially wide range of
infectious and inflammatory diseases.

         We are studying the following two other  imaging  products  pursuant to
Investigational  New Drug  applications  that we have filed or plan to file with
the FDA and we have ongoing clinical trials in Europe:

*        LymphoScan(R), for non-Hodgkin's B-cell lymphomas.

*        AFP-Scan(R), for liver cancer and germ-cell tumors of the ovaries and
         testes.

         Therapeutic Products

         We are applying our expertise in antibody  selection,  modification and
chemistry  to cancer  therapeutics,  using  monoclonal  antibodies  labeled with
therapeutic radioisotopes or conjugated with drugs. We are engaged in developing
anti-cancer  products,  principally with a technique called  radioimmunotherapy.
This technique may deliver  radiolabeled  therapeutic agents to tumor sites more
selectively  than  current  radiation  therapy  technologies,  while  minimizing
debilitating side effects. In addition, we are evaluating in clinical trials the
effects of our  non-radioactive  lymphoma  antibody  in  non-Hodgkin's  lymphoma
patients.

         Research Programs

         In addition to concentrating  on our products in clinical  development,
we conduct ongoing research in many related areas. We conduct research  in-house
and in collaboration  with The Center for Molecular Medicine and Immunology also
known as the Garden State Cancer Center and other


                                       13
<PAGE>


academic and research  centers.  In March 1999,  we entered into a joint venture
with Beckman Coulter to develop the next generation of cancer therapeutics using
bi-specific  antibodies.  We believe our ongoing  research efforts will identify
new and improved  products and techniques  for  diagnosing and treating  various
cancers and infectious diseases.

         Our research  efforts are focused in various  areas related to our core
technology,  including  antibody  engineering  and the  identification  of other
antibody-directed  approaches  to  cancer  therapy.  We  have  made  significant
progress in  humanizing  certain  mouse  antibodies  and have  reengineered  the
humanized antibodies with improved  characteristics.  We are continuing our work
on  selective  coupling  of  therapeutic  site  specific  agents  onto  antibody
fragments  which  will  offer the  advantage  of  loading  multiple  therapeutic
compounds  onto  antibodies  at a particular  disease  site. We also continue to
investigate pre-targeting whereby an antibody is administered first, followed by
a radionuclide or drug administration.

         We also  are  continuing  our  research  into  the  use of  alternative
radioisotopes, such as Yttrium-90 in place of Iodine-131. Our research indicates
that  Yttrium-90 is retained by lymphoma cells for longer periods after antibody
metabolism,  and shows greater  efficacy  against  larger  tumors.  We also have
developed a technology using a compound called "DOTA" to tightly bind Yttrium-90
to antibodies.


         In addition,  we are continuing our efforts to scale-up our proprietary
method for technetium-99m radiolabeling of peptides, using single-vial kits.

December 1998 Financing

         On December 9, 1998,  we completed a private  placement of 1,250 shares
of Series F Convertible Preferred Stock to the selling stockholders and received
gross proceeds of $12,500,000.

         Each share of Series F Stock has an initial  stated  value of  $10,000,
which  increases  at the rate of 4% per annum and as of November 9, 1999 equaled
$10,367 per share.  The Series F Stock became  convertible  on June 8, 1999. The
number of shares of common  stock  issuable  upon  conversion  of each  share of
Series F Stock will be  determined  by dividing the stated value of $10,000 plus
an  accretion of 4% per annum,  by the  conversion  price then in effect.  As of
November 9, 1999,  232.5  shares of the Series F Stock had been  converted  into
2,049,931 shares of common stock.

         The conversion price is equal to:

*        the Variable  Price,  if the Variable Price is less than $2.50;  except
         that prior to  December  9, 1999,  subject to  acceleration  in certain
         instances,  if the  Variable  Price is greater than $1.80 and less than
         $2.50, the conversion price will equal $2.50; or

*        $2.50, if the Variable Price is equal to or greater than the $2.50 and
         less than $3.75; or

*        $2.50 plus one-half of the amount,  if any, by which the Variable Price
         exceeds $3.75, if the Variable Price is greater than $3.75.

         The $2.50  conversion price was set based on 125% of the "Initial Fixed
Price" of $2.00,  which was the average  closing  bid price of our common  stock
during the 20 trading days ended June 6, 1999. The "Variable  Price" is equal to
the average of the 15 lowest  closing bid prices for our common stock during the
45 trading days immediately preceding a conversion date. As of November 9, 1999,
the Variable Price was $1.18 per share.

         At any time during the 90-day period commencing on December 1, 1999, we
may, require the selling stockholders to purchase up to an additional $7,500,000
million  (750  shares)  our of Series F Stock.  Our right to require the selling
stockholders to purchase this additional amount is subject to certain conditions
and  limitations,  including  that the Variable Price has been at least equal to
the $2.00 for a specified  period of time.  Given the recent  price at which our
common stock has traded,  it is unlikely that this  condition will be satisfied.
We have  granted the selling  stockholders  certain  participation  rights if we
issue any future floating rate convertible securities. The holders of the Series
F Stock generally do not have the right to vote for the election of directors or
on other matters, except to the extent their rights would be adversely affected.


                                       14
<PAGE>


         Upon the occurrence of certain events, we may be required to redeem the
Series F Stock, pay certain penalties and/or adjust the conversion price.  These
events include the following:

*        If we consolidate,  merge or otherwise  combine with another entity and
         as a result the  stockholders of our company  immediately  prior to the
         transaction do not retain  sufficient  voting power to elect a majority
         of the  board of  directors  of the new or  combined  entity,  then the
         holders of the Series F Stock may require us to redeem  their shares at
         a price per share equal to the greater of

         (1)  125% of the stated value of $10,000 per share plus the accretion
              of 4% per annum, and

         (2)  the  value  of our  common  stock  that  would  be  issuable  upon
              conversion of the Series F Stock.

              However,   if  the   consolidation,   merger  or  other   business
         combination  occurs as a result of a proxy  solicitation  which was not
         approved or recommended by our Board of Directors, then, if the holders
         exercise their redemption rights, we may, in lieu of redemption,

         (y)  readjust  the  Initial  Fixed Price to 80% of the lower of (A) the
              lowest Variable Price during the period  beginning on the date the
              solicitation is announced and ending on the date the  solicitation
              is  consummated,  abandoned or terminated or (B) the Initial Fixed
              Price then in effect, and

         (z)  pay a penalty  of 1% per day of the stated  value of  $10,000  per
              share plus the  accretion of 4% per annum for a maximum of 10 days
              in any 365-day period.

*        If at least a specified  percentage  of the holders of our common stock
         accept a purchase,  tender or exchange  offer,  then the holders of the
         Series F Stock may  require  us to redeem  their  shares at a price per
         share equal to the greater of

         (1)  125% of the stated value of $10,000 per share plus the accretion
              of 4% per annum, and

         (2)  the  value  of our  common  stock  that  would  be  issuable  upon
              conversion of the Series F Stock.

              However,  if the  purchase,  tender  or  exchange  offer  was  not
         approved or recommended by our Board of Directors; then, if the holders
         exercise their redemption rights, we may, in lieu of redemption,

         (y)  readjust  the  Initial  Fixed Price to 80% of the lower of (A) the
              lowest Variable Price during the period  beginning on the date the
              offer  is   announced   and  ending  on  the  date  the  offer  is
              consummated,  abandoned  or  terminated  or (B) the Initial  Fixed
              Price then in effect, and

         (z)  pay a penalty  of 1% per day of the stated  value of  $10,000  per
              share plus the  accretion of 4% per annum for a maximum of 10 days
              in any 365-day period.

*        If we complete a sale of all or substantially  all of our assets,  then
         the holders of the Series F Stock may require us to redeem their shares
         at a price per share equal to the greater of

         (1)  125% of the stated value of $10,000 per share plus the accretion
              of 4% per annum, and

         (2)  the  value  of our  common  stock  that  would  be  issuable  upon
              conversion of the Series F Stock.

o        If the  registration  statement  ceases to be  available to the selling
         stockholders  for the  resale of their  shares in  accordance  with the
         terms of the registration rights agreement for more than 10 consecutive
         days,  then the holder of the  Series F Stock may  require us to redeem
         their shares at a price per share equal to the greater of

         (1)  125% of the stated value of $10,000 per share plus the accretion
              of 4% per annum, and


                                       15
<PAGE>


         (2)  the  value  of our  common  stock  that  would  be  issuable  upon
              conversion of the Series F Stock.

              However, if the unavailability of the registration  statement does
         not result  from our  failure  to use our best  efforts,  then,  if the
         holders  exercise  their  redemption   rights,   we  may,  in  lieu  of
         redemption,

         (y)  pay a penalty  of 1% per day of the stated  value of  $10,000  per
              share plus the  accretion of 4% per annum for a maximum of 15 days
              in any 365-day period, and

         (z)  readjust  the Initial  Fixed  Price to 80% of the lowest  Variable
              Price  during the period  commencing  on the day the  registration
              statement   became   unavailable   and   ending  on  the  day  the
              registration statement is again available for use.

*        If our common stock is delisted or suspended  from the Nasdaq  National
         Market for a period of more than five consecutive days, then the holder
         of the Series F Stock may require us to redeem  their shares at a price
         per share equal to the greater of

         (1)  125% of the stated value of $10,000 per share plus the accretion
              of 4% per annum, and

         (2)  the  value  of our  common  stock  that  would  be  issuable  upon
              conversion of the Series F Stock.

              However,  if our common stock is delisted from the Nasdaq National
         Market then, if the holders exercise their redemption  rights,  we may,
         in lieu of redemption,

         (y)  readjust the Initial  Fixed Price to 68.5% of the lowest  Variable
              Price during the period  commencing  on the date of delisting  and
              continuing for 45 days thereafter, or

         (z)  pay a penalty  of 1% per day of the stated  value of  $10,000  per
              share plus the  accretion of 4% per annum for a maximum of 15 days
              in any 365-day period.

         In certain cases, if the events described above occur more than once in
any 365-day period,  there will be a further downward  adjustment of the Initial
Fixed Price.

         Pursuant to our agreement with the selling stockholders, in March 1999,
we held a Special  Meeting of  Stockholders  at which  meeting our  stockholders
approved  the  issuance of any shares upon  conversion  of the Series F Stock in
excess of 20% of the  number of shares  of common  stock we had  outstanding  on
December 9, 1998 (i.e.,  7,577,617) in accordance with the rules and regulations
of The Nasdaq Stock Market, Inc.

         Each selling  stockholder  has agreed that if it engages in short sales
transactions or other hedging  activities during the 45 trading days immediately
preceding a conversion date which involve,  among other things,  sales of shares
of our common  stock,  the  selling  stockholder  will place its sale orders for
common stock in the course of these  activities  so as not to complete or effect
any sale on any trading day during the period at a price which is lower than the
lowest sale effected on that day by persons  other than the selling  stockholder
and its affiliates.

         Because the market price of our common stock is subject to fluctuation,
we had agreed,  pursuant to the terms of a  registration  rights  agreement,  to
register for resale by the selling  stockholders  at least 200% of the number of
shares of common  stock  that would be  issuable  if all the Series F Stock were
converted as of the date of filing of the original  registration  statement and,
thereafter,  maintain the  registration of at least 150% of the number of shares
of common  stock  that  would be  issuable  if all the  Series F Stock were then
converted.  Accordingly,  when we originally filed our registration statement in
December 1998, the prospectus  covered  10,000,000 shares of common stock, which
was our good faith estimate of this obligation at that time. As the registration
statement became  insufficient to permit the resale by the selling  stockholders
of all the common  shares  issuable upon  conversion of the Series F Stock,  the
selling  stockholders,  in addition to any other remedies,  claimed they had the
right to require us to redeem all or any  portion of the  remaining  outstanding
shares of Series F Stock (at a price  equal to the greater of 125% of the stated
value of $10,000 per share plus the  accretion  of 4% per annum and the value of
the Common Stock which would have been issued upon conversion) as well as pay to
them


                                       16
<PAGE>


a penalty  of $5 per share of Series F Stock  with  respect to each day that the
registration statement was insufficient.

         We have  received a waiver,  dated  October 11, 1999,  from the selling
stockholders  with  respect  to the  rights  discussed  above  either to require
redemption  or  to  receive   penalties   conditioned  upon  our  (a)  filing  a
registration  statement,  on or before November 11, 1999, covering at least 200%
of the number of shares of common stock that would be issuable if all the Series
F Stock  were  converted  as of the  date  of the  filing  of this  registration
statement and (b) having this registration  statement  declared  effective on or
before December 11, 1999. However,  if failure of the registration  statement to
be declared  effective  by December 11, 1999 does not result from our failure to
use our best efforts,  then, if the holders exercise their redemption rights, we
may, in lieu of redemption, pay the penalties and adjust the Initial Fixed Price
in the manner described above under the circumstances  where the  unavailability
of the  registration  statement  did not result from our failure to use our best
efforts.  In  addition,  notwithstanding  whether  or not we have  used our best
efforts, if the registration statement is not declared effective by December 11,
1999, the selling  stockholders  also will be entitled to the $5 per day penalty
(discussed  above)  accruing  from the  first day that we were in breach of this
registration obligation, which penalties would be significant.

         In addition, until the registration statement is declared effective, we
will be unable to exercise  certain of our rights  with  respect to the Series F
Stock and assuming that we had otherwise  satisfied the other  conditions to the
exercise of these rights, including (a) the right, upon 20 days advanced notice,
to redeem all of the  outstanding  shares of Series F Stock at a 20%  annualized
premium,  and (b) the right,  upon three days  advanced  notice,  to require the
selling stockholders to convert their Series F Stock if the closing bid price of
our common stock had exceeded $5.00 for a specified period of time. We will lose
these  rights  altogether  if we fail  to file  the  registration  statement  by
November 11, 1999 or fail to use our best efforts to have it declared  effective
by December 11, 1999. We intend to use our best efforts to have the registration
statement  declared  effective on or before December 11, 1999 although we cannot
assure you that the  registration  will be declared  effective by that date.  We
continue to have the right, upon five days advanced notice, to redeem any or all
shares of Series F Stock presented for conversion at a conversion  price of less
than $1.80 at a  redemption  price equal to 105% of the stated  value of $10,000
per share plus the accretion of 4% per annum.

         While  this  registration  statement  covers  an  additional  9,878,463
shares of our common stock in addition to the  7,950,069  shares of common stock
included in our prior  prospectus,  we would not be required to issue any shares
which are the  subject  of this  additional  registration  statement  unless the
Variable  Price at the time of conversion  on average is below $1.33  (increased
over  time  due  to  the  4%  accretion  to  the  stated  value).  See  "Selling
Stockholders" for information concerning the number of shares that are currently
issuable.

         We also plan to  continue  our  separate  discussions  with each of the
selling stockholders  concerning a possible restructuring of certain other terms
of the Series F Stock.  However, we cannot assure you that any restructuring can
be accomplished upon terms we find acceptable, if at all.

         If we were  required  to redeem  the  Series F Stock or make any of the
penalty payments,  we may not have the financial ability to make these payments.
Even if we did have the  financial  ability  to redeem the Series F Stock or pay
the required  penalties,  any payments could  significantly and adversely affect
our financial condition and deplete its cash resources.

         In connection with our agreement with the selling stockholders, we have
agreed to  reimburse  them for up to $50,000 of their  legal  expenses  they had
incurred in connection with the issuance of the Series F Stock.


                                 Use of Proceeds

         We will not receive any  proceeds  from the sale of our common stock by
the selling stockholders.  However, we did receive net proceeds of approximately
$12,330,000 from the issuance of the Series F Stock to the selling  stockholders
in December 1998.

         We intend to  continue  to use these  proceeds  for  general  corporate
purposes,  including  research  and  development,  clinical  trials,  regulatory
filings, manufacturing, marketing and sales, general and


                                       17
<PAGE>


administrative  and other expenses,  acquisitions of products and  technologies,
license,  milestone,  royalty  and similar  payments,  and  strategic  and other
acquisitions.


                              Selling Stockholders

         The table below presents the following  information:  (1) the number of
shares of Series F Stock  owned by each  selling  stockholder  as of the date of
this prospectus,  (2) the number of shares of common stock beneficially owned by
each selling  stockholder as of the date of this  prospectus,  (3) the number of
shares that the selling  stockholder is offering under this prospectus,  and (4)
the number of shares that the selling  stockholder  will  beneficially own after
the completion of this offering.

         Except as otherwise  noted in the table,  the number and  percentage of
shares  beneficially  owned by each selling  stockholder is determined as of the
date of this prospectus in accordance with Rule 13d-3 of the Securities Exchange
Act, and the information is not necessarily  indicative of beneficial  ownership
for any other purpose. Under this rule, beneficial ownership includes any shares
as to  which  the  selling  stockholder  has  sole or  shared  voting  power  or
investment power and also any shares which the selling stockholder has the right
to acquire within 60 days of the date of this prospectus  through the conversion
of the Series F Stock or the exercise of any stock option or other right. Unless
otherwise indicated in the footnotes, each person has sole voting and investment
power with respect to the shares shown as beneficially owned.

         The number of shares of our common stock shown as beneficially owned by
each selling  stockholder prior to the offering and the number of shares offered
by each selling stockholder represents shares of our common stock issuable to it
assuming  conversion,  as of November  9, 1999,  of all shares of Series F Stock
owned by that selling  stockholder  with respect to the $10,000  stated value of
the Series F Stock plus an  accretion  of 4% per year.  The number of shares was
calculated  using an assumed  conversion  price of $1.18,  which  represents the
average of the 15 lowest  closing bid prices for our common  stock during the 45
consecutive trading days ending on November 8, 1999. As described in the section
"Immunomedics - December 1998 Financing"  above,  the actual number of shares of
our common stock  issuable  upon  conversion of the Series F Stock is based upon
the market price of common stock at the time of conversion.  In accordance  with
the provisions of the Series F Stock,  the conversion  price will fluctuate from
time to  time  based  on  changes  in the  market  price  of our  common  stock.
Therefore,  the actual  number of shares of common  stock may be less or greater
than  the  number  of  shares  shown  as  beneficially   owned  by  the  selling
stockholders  or the  number of shares  offered  by this  prospectus.  Under the
certificate of designation  for the Series F Stock,  no selling  stockholder can
convert Series F Stock to the extent that the conversion would cause the selling
stockholder's  beneficial  ownership  of our common stock to exceed 4.99% of our
outstanding   common  stock,  or  1,992,907  shares  at  November  9,  1999.  In
calculating a selling  stockholder's  beneficial ownership for this purpose, the
selling  stockholder  would  exclude any shares which it would be  considered to
beneficially own through ownership of unconverted Series F Stock.

         The number of shares that will  ultimately be issued upon conversion of
the  Series F Stock is  dependent,  subject  to  certain  limitations,  upon the
average of certain closing bid prices of our common stock prior to conversion as
discussed  above.  Accordingly,  the number of shares that may be issued and the
number of shares  offered hereby cannot be determined at this time. As a result,
as discussed  above,  we have agreed to register for resale at least 200% of the
number of shares of common  stock  that  would be  issuable  if all the Series F
Stock were converted as of the date of this prospectus.  As of November 9, 1999,
we would  have been  required  to issue  approximately  8,914,266  shares of our
common  stock  had  the  holders   converted  all  of  their  1,017.5  remaining
outstanding  shares of Series F Stock on this date. As discussed  above, we have
agreed to  register  17,828,532  shares of our common  stock.  Accordingly,  the
selling stockholders may be entitled to sell approximately  8,914,266 additional
shares  pursuant  to this  prospectus,  if these  shares  are  issued to them in
accordance with the terms of the Series F Stock.

         The number of shares shown as being  beneficially owned by each selling
stockholder after the offering assumes that the selling stockholder has sold all
the shares of our common stock which may be sold pursuant to this prospectus.

         None of the selling  stockholders has had a material  relationship with
us within the past three  years,  other  than as a result of their  purchase  of
shares of our Series F Stock. As of November 9, 1999,


                                       18
<PAGE>


no  selling  stockholder  owned any shares of our  common  stock  other than the
shares they may acquire upon conversion of the Series F Stock, other than Fisher
Capital Ltd. which  directly  owned 128,740 shares of our common stock,  Wingate
Capital  Ltd.  which  directly  owned  77,269  shares  of our  common  stock and
Leonardo, L.P. which directly owned 617 shares of common stock.

<TABLE>
<CAPTION>
                                                                      Shares of                             Shares of
                                                     Shares of       Common Stock                          Common Stock
                                                     Preferred       Beneficially        Shares of         Beneficially
                                                       Stock        Owned Prior to      Common Stock       Owned After
Selling Stockholder                                    Owned         the Offering      Being Offered         Offering
- --------------------                                   -----         ------------      -------------         --------
<S>                                                  <C>            <C>                <C>                 <C>
AG Super Fund International Partners,
L.P.(1)                                                 20.0            175,219            175,219                  0
Fisher Capital Ltd.(2)                                 120.0          1,180,054          1,051,314            128,740
GAM Arbitrage investments, Inc.(1)                      18.0            157,697            157,697                  0
HFTP Investment L.L.C.(3)                              550.0          4,818,522          4,818,522                  0
Leonardo, L.P.(1)                                      187.5          1,643,291          1,643,291                  0
Ramius Fund, Ltd.(1)                                    38.0            332,916            332,916                  0
Raphael, L.P.(1)                                        20.0            175,219            175,219                  0
Wingate Capital Ltd.(2)                                 64.0            637,970            560,701             77,269
- ----------------

</TABLE>

(1)      Angelo, Gordon & Co., L.P. is a general partner of Leonardo, L.P., AG
         Super Fund International Partners, L.P. and Raphael, L.P., and is
         investment advisor to GAM Arbitrage Investments, Inc. and Ramius Fund,
         Ltd. and consequently has voting control and investment discretion over
         securities held by these entities.  The ownership for each of these
         entities does not include the ownership information for the other
         entities.  Angelo, Gordon & Co., L.P. and each of the referenced
         entities disclaims beneficial ownership of any of our securities held
         by the other referenced entities.  Mr. John M. Angelo, the Chief
         Executive Officer of Angelo, Gordon & Co., L.P., and Mr. Michael R.
         Gordon, the Chief Operating Officer of Angelo, Gordon & Co., L.P., are
         the sole general partners of AG Partners, L.P., which is the sole
         general partner of Angelo, Gordon & Co., L.P.  In this capacity,
         Messrs.  Angelo and Gordon may be deemed to be the beneficial owner of
         any our securities deemed to be beneficially owned by Angelo, Gordon &
         Co., L.P.  However, Messrs. Angelo and Gordon disclaim beneficial
         ownership of these securities.

(2)      Citadel Limited Partnership is the trading manager of Wingate Capital
         Ltd. and Fisher Capital  Ltd. and consequently has voting control and
         investment discretion over securities held by these entities.  Citadel
         Limited Partnership is indirectly controlled by Mr. Kenneth C. Griffin.
         The ownership for each referenced entity does not include the ownership
         information for the other referenced entity.  Citadel Limited
         Partnership and each of the referenced entities disclaims beneficial
         ownership of any of our securities held by the other entities.  Mr.
         Griffin may be deemed to be the beneficial ownership of any of our
         securities beneficially owned by Citadel Limited Partnership or the
         referenced entities.  However, Mr. Griffin disclaims beneficial
         ownership of these securities.

(3)      Promethean Investment Group L.L.C. is the investment advisor for HFTP
         Investment L.L.C. and consequently has voting control and investment
         discretion over securities held by this entity.  Promethean Investment
         Group L.L.C. is indirectly controlled by Mr. James F. O'Brien, Jr.
         Promethean Investment Group L.L.C. disclaims beneficial ownership of
         any of our securities  held by HFTP Investment L.L.C.  Mr. O'Brien may
         be deemed to be the beneficial ownership of any of our securities
         beneficially owned by Promethean Investment Group L.L.C. or HFTP
         Investments L.L.C.  However, Mr. O'Brien disclaims beneficial ownership
         of these securities.  As a result of the limitation discussed above in
         this section, the selling stockholder would be prevented from
         converting Series F Stock to the extent that the conversion would
         cause the


                                       19
<PAGE>


         selling  stockholder's  beneficial  ownership  of our  common  stock to
         exceed 4.99% of our outstanding common stock.


                              Plan of Distribution

Manner of Sales; Broker-Dealer Compensation.

         The selling stockholders,  or any successors in interest to the selling
stockholders,  may sell any shares of common  stock that they  acquire when they
convert  shares of Series F Stock.  The sale of our common stock may be effected
in one or more of the following methods:

*        ordinary brokers' transactions;

*        transactions involving cross or block trades or otherwise on the Nasdaq
         National Market;

*        purchases by brokers, dealers or underwriters as principal and resale
         by these purchasers for their own accounts pursuant to this prospectus;

*        "at the market" to or through market makers or into an existing market
         for our common stock;

*        in other  ways not  involving  market  makers  or  established  trading
         markets,  including direct sales to purchases or sales effected through
         agents;

*        through transactions in options, swaps or other derivatives (whether
         exchange-listed or otherwise);

*        in privately negotiated transactions;

*        to cover short sales; or

*        any combination of the foregoing.

         The selling stockholders also may sell the shares in reliance upon Rule
144 under the  Securities  Act at such times as they are  eligible  to do so. We
have  been  advised  by the  selling  stockholders  that  they have not made any
arrangements  for the  distribution  of the  shares  of common  stock.  Brokers,
dealers  or  underwriters  who effect  sales for the  selling  stockholders  may
arrange for other brokers,  dealers or  underwriters  to  participate.  Brokers,
dealers  or  underwriters  engaged  by the  selling  stockholders  will  receive
commissions  or  discounts  from them in amounts to be  negotiated  prior to the
sale. These brokers, dealers or underwriters may act as agent or as principals.

         From time to time, one or more of the selling  stockholders may pledge,
hypothecate or grant a security  interest in some or all of the shares of common
stock acquired by them upon conversion of the Series F Stock,  and the pledgees,
secured  parties or persons to whom these  securities  have been pledged  shall,
upon foreclosure in the event of default,  be considered a selling  stockholders
hereunder.  In addition,  subject to the limitations  discussed above, a selling
stockholder  may,  from time to time,  sell  short our  common  stock.  In these
instances, this prospectus may be delivered in connection with these short sales
and the shares of our common stock issued upon  conversion of Series F Stock may
be used to cover these short sales.

         From time to time one or more of the selling stockholders may transfer,
pledge,  donate or assign  shares of our  common  stock  that it  acquired  upon
conversion of Series F Stock to lenders or others and each of these persons will
be considered a selling stockholder for purposes of this prospectus.  The number
of shares of our common stock beneficially  owned by those selling  stockholders
who so  transfer,  pledge,  donate or assign  shares of our  common  stock  will
decrease as and when they take these actions.  The plan of distribution  for our
common stock by the selling stockholders' set forth herein will otherwise remain
unchanged,  except that the  transferees,  pledgees,  donees or other successors
will be considered selling stockholders hereunder.

          Subject to the limitations discussed above, a selling stockholder may
enter into hedging


                                       20
<PAGE>


transactions  with  broker-dealers  and the  broker-dealers  may engage in short
sales of our common  stock in the course of hedging  the  positions  they assume
with this selling stockholder, including in connection with distributions of our
common stock by these broker-dealers.  A selling stockholder may also enter into
option or other  transactions with  broker-dealers  that involve the delivery of
our  common  stock to the  broker-dealers,  who may  then  resell  or  otherwise
transfer these shares. A selling  stockholder also may loan or pledge our common
stock to a  broker-dealer  and the  broker-dealer  may sell our common  stock so
loaned or upon a default  may sell or  otherwise  transfer  the  pledged  common
stock.

Filing of a Post-Effective Amendment In Certain Instances.

         If any  selling  stockholder  notifies  us that it has  entered  into a
material arrangement (other than a customary brokerage account agreement) with a
broker or dealer for the sale of shares of common  stock  under this  prospectus
through a block trade, purchase by a broker or dealer or similar transaction, we
will file a  post-effective  amendment to the  registration  statement under the
Securities Act. The post-effective amendment will disclose:

*        The name of each broker-dealer involved in the transaction.

*        The number of shares of common stock involved.

*        The price at which those shares of common stock were sold.

*        The commissions paid or discounts or concessions allowed to the broker-
         dealer(s).

*        If  applicable,   that  these  broker-dealer(s)  did  not  conduct  any
         investigation  to verify the  information  contained or incorporated by
         reference in this prospectus, as supplemented.

*        Any other facts material to the transaction.

Certain Persons May Be Deemed to Be Underwriters

         The selling  stockholders and any  broker-dealers who execute sales for
them may be deemed to be "underwriters" within the meaning of the Securities Act
because  of the  number of shares of common  stock to be sold or resold by these
persons or entities or the manner of sale of these shares, or both. If a selling
stockholder  or  any  broker-dealer  or  other  holders  were  determined  to be
underwriters,  any discounts,  concessions or commissions received by them or by
brokers or dealers  acting on their  behalf and any profits  received by them on
the resale of their  shares of common  stock might be deemed to be  underwriting
discounts and commissions under the Securities Act.

Regulation M

         We have informed the selling stockholders that Regulation M promulgated
under the Securities  Exchange Act may be applicable to them with respect to any
purchase or sale our common  stock.  In  general,  Rule 102 under  Regulation  M
prohibits  any person  connected  with a  distribution  of our common stock from
directly or indirectly  bidding for, or  purchasing  for any account in which it
has a beneficial interest,  any of our common stock or any right to purchase our
common  stock,  for a period of one business day before and after  completion of
its participation in the distribution.

         During any  distribution  period,  Regulation  M prohibits  the selling
stockholders and any other persons engaged in the distribution  from engaging in
any  stabilizing  bid or  purchasing  our common stock except for the purpose of
preventing  or retarding a decline in the open market price of our common stock.
None of these persons may effect any  stabilizing  transaction to facilitate any
offering  at the market.  As the selling  stockholders  will be  reoffering  and
reselling  our common stock at the market,  Regulation M will prohibit them from
effecting any  stabilizing  transaction  in  contravention  of Regulation M with
respect to our common stock.

Indemnification and Other Matters

         We paid all of the expenses incident to the registration,  offering and
sale of our common  stock by the selling  stockholders  to the public other than
commissions or discounts of underwriters,


                                       21
<PAGE>


broker-dealers  or  agents.  We also have  agreed to  indemnify  certain  of the
selling  stockholders  and certain related persons against certain  liabilities,
including  liabilities under the Securities Act. Insofar as indemnification  for
liabilities  arising under the Securities Act may be permitted to our directors,
officers and  controlling  persons,  we have been advised that in the opinion of
the SEC this indemnification  agreement is against public policy as expressed in
the Securities Act and is, therefore, unenforceable.

         This  offering  will  terminate on the earlier of (a) the date on which
the shares are eligible for resale without  restriction  pursuant to Rule 144(k)
under the Securities Act or (b) the date on which all shares offered hereby have
been sold by the selling stockholders.


                                  Legal Matters

         Warshaw Burstein Cohen  Schlesinger & Kuh, LLP will give its opinion on
the validity of the common  stock.  As of the date of this  prospectus,  certain
partners of this firm  beneficially  own an  aggregate of 1,200 shares of common
stock.


                                     Experts

         Our consolidated financial statements as of June 30, 1999 and 1998, and
for each of the years in the  three-year  period  ended June 30,  1999 have been
incorporated by reference herein and in the  registration  statement in reliance
upon  the  report  of  KPMG  LLP,  independent   certified  public  accountants,
incorporated by reference herein, and upon the authority of said firm as experts
in accounting and auditing.



                                       22
<PAGE>



                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.   Other Expenses of Issuance and Distribution.

         The following is an itemized  statement of the estimated amounts of all
expenses payable by us in connection with the registration of the Shares:


SEC registration fee.........................................  $           3,261
Legal fees and expenses......................................             15,000
Accounting fees and expenses.................................              4,000
Miscellaneous expenses.......................................              1,739
                                                               -----------------
         Total...............................................  $          24,000
                                                               =================

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

Item 15.   Indemnification of Directors and Officers.

                  The Delaware General  Corporation Law provides,  in substance,
that Delaware corporations shall have the power, under specified  circumstances,
to indemnify their directors,  officers, employees and agents in connection with
actions  or suits by or in the right of the  corporation,  by reason of the fact
that they were or are such directors,  officers,  employees and agents,  against
expenses  (including  attorneys'  fees) and,  in the case of  actions,  suits or
proceedings brought by third parties,  against judgment,  fines and amounts paid
in  settlement  actually and  reasonably  incurred in any such  action,  suit or
proceeding.

                  The Company's  Certificate  of  Incorporation  provides that a
director shall not be personally  liable to the Company or its  stockholders for
monetary damages for breach of fiduciary duty as a director except for liability
(i)  for  breach  of the  director's  duty  of  loyalty  to the  Company  or its
stockholders,  (ii) for acts or  omissions  not in good  faith or which  involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
the Delaware General Corporation Law, or (iv) for any transaction from which the
director derived an improper personal benefit. The Company's Bylaws also provide
that the Company may indemnify its directors, officers and legal representatives
to the fullest extent  permitted by Delaware law against all awards and expenses
(including attorneys' fees).

Item 16.   Exhibits.

Exhibit No.       Description

  4.1         -    Securities  Purchase  Agreement, dated as of December 9 1998,
                   by  and  among  the  Company  and the investors named therein
                   (incorporated  by  reference  to  Exhibit 10.1 to the Current
                   Report  on  Form  8-K,  filed  by the Company on December 15,
                   1998).

  4.2         -    Registration  Rights Agreement, dated as of December 9, 1998,
                   by  and  among  the  Company  and the investors named therein
                   (incorporated  by  reference  to Exhibit 10.2 to  the Current
                   Report  on  Form  8-K,  filed  by the Company on December 15,
                   1998).

  4.3         -    Certificate of Designations, Preferences and Rights of Series
                   F Convertible Preferred Stock (incorporated  by reference  to
                   Exhibit 3.1 to the Current  Report on Form 8-K,  filed by the
                   Company on December 15, 1998).

  4.4         -    Form  of  Waiver,  dated  October  11, 1999, by and among the
                   Company and the investors named therein.

  5           -    Opinion of Warshaw Burstein Cohen Schlesinger & Kuh, LLP.



<PAGE>


 23.1         -    Consent of KPMG LLP.

 23.2         -    Consent  of  Warshaw  Burstein  Cohen  Schlesinger & Kuh, LLP
                   (included in their opinion filed as Exhibit 5).

 24           -    Power of Attorney (included on page II-4).


Item 17.   Undertakings.

         The Company hereby  undertakes  that,  for purposes of determining  any
liability under the Securities Act of 1933, each filing of the Company's  annual
report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act
of 1934 (and, where applicable, each filing of an employee benefit plan's annual
report pursuant to section 15(d) of the Securities Exchange Act of 1934) that is
incorporated by reference in the registration  statement shall be deemed to be a
new registration  statement relating to the securities offered therein,  and the
offering of such  securities at that time shall be deemed to be the initial bona
fide offering thereof.

         The Company undertakes that it will:

                  (1)  File,  during  any  period  in which it  offers  or sells
         securities,  a post-effective  amendment to this registration statement
         to:

                           (i)   Include  any   prospectus  require  by  section
                  10(a)(3) of the Securities Act;

                           (ii)  Reflect in the  prospectus  any facts or events
                  which,  individually  or  together,  represent  a  fundamental
                  change in the information in the registration statement.

                           Notwithstanding   the  foregoing,   any  increase  or
                  decrease in volume of securities  offered (if the total dollar
                  value of  securities  offered  would not exceed that which was
                  registered)  and any deviation from the low or high end of the
                  estimated  maximum offering range may be reflected in the form
                  of  prospectus  filed  with the  Commission  pursuant  to Rule
                  424(b) if, in the  aggregate,  the changes in volume and price
                  represent  no more than a 20% change in the maximum  aggregate
                  offering price set forth in the  "Calculation  of Registration
                  Fee" table in the effective registration statement.

                           (iii) Include any material  information  with respect
                  to the plan of  distribution  not previously  disclosed in the
                  registration   statement  or  any  material  changes  to  such
                  information in the registration statement.

                  provided,  however, that the Company does not need to give the
         statements  in paragraph  (a)(1)(i) and  (a)(1)(ii) if the  information
         required in a  post-effective  amendment is  incorporated  by reference
         from periodic reports filed by the Company under the Exchange Act.

                  (2) For determining  liability under the Securities Act, treat
         each  post-effective  amendment as a new registration  statement of the
         securities offered,  and the offering of the securities at that time to
         be the initial bona fide offering.

                  (3)  File  a   post-effective   amendment   to   remove   from
         registration any of the securities that remain unsold at the end of the
         offering.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 (the "Act") may be permitted to directors,  officers and controlling
persons of the Company pursuant to the foregoing provisions,  or otherwise,  the
Company has been  advised  that in the opinion of the  Securities  and  Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable.

         In the event that a claim for indemnification  against such liabilities
(other  than the  payment  by the  Company  of  expenses  incurred  or paid by a
director, officer or controlling person of the Company in the successful defense
of any action, suit or proceeding) is asserted by such director, officer or


                                      II-2
<PAGE>


controlling  person in connection  with the  securities  being  registered,  the
Company  will,  unless in the opinion of its counsel the matter has been settled
by  controlling  precedent,  submit to a court of appropriate  jurisdiction  the
question  whether  such  indemnification  by  it is  against  public  policy  as
expressed in the Securities  Act and will be governed by the final  adjudication
of such issue.




                                      II-3
<PAGE>


                                   SIGNATURES

         Pursuant  to the  requirements  of the  Securities  Act  of  1933,  the
Registrant  certifies that it has reasonable  grounds to believe it meets all of
the  requirements  for filing on Form S-3 and has duly caused this  Registration
Statement  to be  signed  on its  behalf  by  the  undersigned,  thereunto  duly
authorized,  in the City of Morris Plains,  State of New Jersey,  on November 9,
1999.

                                                              IMMUNOMEDICS, INC.


                                                     By: /s/ David M. Goldenberg
                                                     ---------------------------
                                                             David M. Goldenberg
                                                       Chairman of the Board and
                                                         Chief Executive Officer
                                                   (Principal Executive Officer)

         Each person whose  signature  appears  below  constitutes  and appoints
David M.  Goldenberg,  Cynthia  Sullivan and Shailesh R. Asher and each of them,
his or her true and lawful attorney-in-fact, with full power of substitution and
resubstitution,  for him or her and in his or her name,  place and stead, in any
and all  capacities  to sign any and all  amendments,  including  post-effective
amendments,  to this  Registration  Statement,  and to file the  same,  with all
exhibits  thereto,  and  other  documents  in  connection  therewith,  with  the
Securities and Exchange  Commission  under the  Securities  Act of 1933,  hereby
ratifying and confirming all that said  attorneys-in-fact  or  substitutes,  may
lawfully do or cause to be done by virtue thereof.

         Pursuant  to the  requirements  of the  Securities  Act of  1933,  this
Registration  Statement  has been signed below by the  following  persons in the
capacities and on the dates indicated.

Dated:

November 9, 1999                                   /s/ David M. Goldenberg
                                                   -----------------------------
                                                   David M. Goldenberg, Chairman
                                                   of the Board, Chief Executive
                                                   Officer and a Director
                                                   (Principal Executive Officer)


November 9, 1999                                   /s/ Marvin E. Jaffe
                                                   -----------------------------
                                                   Marvin E. Jaffe, Director


November 9, 1999                                   /s/ Richard R. Pivirotto
                                                   -----------------------------
                                                   Richard R. Pivirotto,
                                                   Director


November 9, 1999                                   /s/ Richard C. Williams
                                                   -----------------------------
                                                   Richard C. Williams, Director


November 9, 1999                                   /s/ Shailesh R. Asher
                                                   -----------------------------
                                                   Shailesh R. Asher, Controller
                                                   and Acting Chief Financial
                                                   Officer (Principal Financial
                                                   and Accounting Officer)


                                      II-4
<PAGE>


4.4               -        Form or Waiver, dated October 11, 1999,  by and among
                           the Company and the investors named therein.

5                 -        Opinion of Warshaw Burstein Cohen Schlesinger & Kuh,
                           LLP.

23.1              -        Consent of KPMG LLP.


                                      II-5
<PAGE>


                                                                     EXHIBIT 4.4

                                WAIVER AGREEMENT

         This Waiver  Agreement  (this  "Waiver") is made and entered into as of
October 11, 1999, by and among Immunomedics,  Inc., a Delaware  corporation (the
"Company"), and the undersigned buyers (the "Buyers").

                                     RECITAL

                  WHEREAS,   under  Section  3(b)  of  the   Company's   Amended
Certificate of Designations,  Preferences and Rights of the Series F Convertible
Preferred  Stock,  as filed with the Secretary of State of the State of Delaware
on December 9, 1998 (the "Certificate of Designations"),  the Buyers, as holders
of shares of the Company's Series F Convertible  Preferred Stock (the "Preferred
Shares")  have the right to require  the Company to redeem all or any portion of
the Preferred  Shares upon the  occurrence of certain  events,  including if the
Registration  Statement  (as  defined in the  Certificate  of  Designations)  is
unavailable to the holders of the Preferred  Shares for sale of the  Registrable
Securities (as defined in the  Certificate of  Designations)  in accordance with
the terms of the Registration Rights Agreement, by and among the Company and the
Buyers,  dated  December 9, 1998 (the  "Registration  Rights  Agreement")  (such
occurrence for redemption, a "Registration Default").

                  WHEREAS,   under  Section  2(g)  of  the  Registration  Rights
Agreement,  the Company is subject to certain cash penalties upon the occurrence
of a Registration Default.

                  NOW,  THEREFORE,  in  consideration  of  the  mutual  promises
contained herein:

                  1.       Waiver.

                           1.1      Each  of  the Buyers hereby waives its right
to  require  redemption  of its  Preferred  Shares  under  Section  3(b)  of the
Certificate of  Designations  as a result of the  Registration  Default which is
currently  existing and which continues so long as the following proviso remains
true, provided that the Company shall (i) file a new Registration Statement with
the Securities  and Exchange  Commission  (the "SEC") on or before  November 11,
1999,  which  Registration  Statement  shall  register for resale that number of
shares of the Company's  Common  Stock,  par value  $0.01per  share (the "Common
Stock"),  equal to the  product  of (x) 2.0 and (y) the  number  of  Registrable
Securities  as of the date  immediately  preceding  the date  such  Registration
Statement  is filed  with the SEC,  less that  number of shares of Common  Stock
which,  as of the date  immediately  preceding  the filing of such  Registration
Statement, are currently registered on Registration Statements for the resale of
shares of Common  Stock by the Buyers and (ii) use its best efforts to have such
Registration  Statement  declared effective by the SEC on or before December 11,
1999 or, if not  achieved  by such date,  until  such date as such  Registration
Statement is declared effective,  provided that the Company continues to use its
best efforts to have such Registration Statement declared effective by the SEC.

                           1.2      Each  of  the Buyers hereby waives its right
to receive the  Registration  Delay  Payments  (as  defined in the  Registration
Rights  Agreement)  that are currently due and any  Registration  Delay Payments
that shall accrue due to the Registration  Default currently  existing as of the
date  hereof,  provided  that the  Company  shall  (i)  file a new  Registration
Statement  with the SEC on or  before  November  11,  1999,  which  Registration
Statement  shall register for resale that number of shares of Common Stock equal
to the product of (x) 2.0 and (y) the number of Registrable Securities as of the
date immediately  preceding the date such  Registration  Statement is filed with
the SEC,  less that  number of shares  of  Common  Stock  which,  as of the date
immediately preceding the filing of such Registration  Statement,  are currently
registered on  Registration  Statements for the resale of shares of Common Stock
by the Buyers and (ii) have such Registration  Statement  declared  effective by
the SEC on or before December 11, 1999.

                           1.3      If  (i)  a new Registration Statement is not
filed with the SEC on or before  November 11, 1999,  registering for resale that
number of shares of Common  Stock  equal to the  product  of (x) 2.0 and (y) the
number of Registrable  Securities as of the date immediately  preceding the date
such Registration Statement is filed with the SEC, less that number of shares of
Common Stock which, as of the


                                      II-6
<PAGE>


date  immediately  preceding  the  filing of such  Registration  Statement,  are
currently  registered  on  Registration  Statements  for the resale of shares of
Common  Stock by the  Buyers  or (ii)  such new  Registration  Statement  is not
declared effective by the SEC on or before December 11, 1999, then:

                                    1.3.1 None of the  Buyers'  waivers of their
                  rights  to  receive   Registration  Delay  Payments  shall  be
                  effective and such Registration Delay Payments shall be deemed
                  to have accrued from the date of the Registration Default; and

                                    1.3.2  None of the  Buyers  waivers of their
                  rights of  redemption in the event of a  Registration  Default
                  shall be  effective  and such  Buyers  shall  be  entitled  to
                  exercise  their right of  Redemption  under  Sections 3(b) and
                  3(f) of the Certificate of Designations, provided, however, if
                  the Company  shall have  satisfied  the  conditions of Section
                  1.1, then the waiver of the Buyers' right of redemption  shall
                  remain in effect except that an Excluded  Redemption Event (as
                  defined  in  the  Certificate  of  Designations)  pursuant  to
                  Section  3(h)(ii) of the Certificate of Designations  shall be
                  deemed to have  occurred,  the Company shall be deemed to have
                  delivered  a Company's  Excluded  Redemption  Event  Notice on
                  December  12,  1999 with  respect to such  events  pursuant to
                  Section 3(h) of the Certificate of Designations and the Buyers
                  shall be entitled to exercise their rights under Sections 3(h)
                  and 3(i) of the Certificate of Designations accordingly.

                           1.4      Provided  that  the Company shall (i) file a
new  Registration  Statement with the SEC on or before November 11, 1999,  which
Registration Statement shall register for resale that number of shares of Common
Stock  equal  to the  product  of (x)  2.0 and (y)  the  number  of  Registrable
Securities  as of the date  immediately  preceding  the date  such  Registration
Statement  is filed  with the SEC,  less that  number of shares of Common  Stock
which,  as of the date  immediately  preceding  the filing of such  Registration
Statement, are currently registered on Registration Statements for the resale of
shares of Common  Stock by the Buyers and (ii) use its best efforts to have such
Registration  Statement  declared effective by the SEC on or before December 11,
1999,  then (A) the  Company  shall be deemed  not to have  breached  either the
Registration  Rights  Agreement or the  Certificate of  Designations  due to the
Registration  Default  currently  existing  as of the date  hereof and which may
continue  until such time as the Company  fails to use its best  efforts to have
such Registration  Statement declared effective by the SEC on or before December
11, 1999 or, if not achieved by such date, until such date as such  Registration
Statement is declared effective,  provided that the Company continues to use its
best efforts to have such Registration  Statement  declared effective by the SEC
and (B) a Triggering Event (as defined in the Certificate of Designations) shall
be deemed not to have  occurred  due to the  Registration  Default  currently in
existence  as of the date hereof and which may  continue  until such time as the
Company  fails to use its  best  efforts  to have  such  Registration  Statement
declared effective by the SEC on or before December 11, 1999 or, if not achieved
by such  date,  until  such  date as such  Registration  Statement  is  declared
effective,  provided that the Company  continues to use its best efforts to have
such Registration Statement declared effective by the SEC.

         2.       Miscellaneous.

                  2.1 Other Provisions.  All other provisions of the Certificate
of Designations and the Registration Rights Agreement shall remain in full force
and effect.

                  2.2 Counterparts. This Waiver may be executed in any number of
counterparts,  each of which  shall be an  original,  but all of which  together
shall constitute one instrument.

                                  * * * * * * *

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


COMPANY:                                          BUYERS:


                                      II-7
<PAGE>


IMMUNOMEDICS, INC.                                [Name of Buyer]


By:______________________                          By:__________________________
Name: David M. Goldenberg                          Name:
Its: Chairman of the Board and Chief               Its:
              Executive Officer


                                      II-8
<PAGE>



                                                                       EXHIBIT 5
                             WARSHAW BURSTEIN COHEN
                             SCHLESINGER & KUH, LLP
                                555 Fifth Avenue
                            New York, New York 10017
                            Telephone: (212) 984-7700
                            Facsimile: (212) 972-9150

                                                                November 9, 1999


Immunomedics, Inc.
300 American Road
Morris Plains, New Jersey 07950

Gentlemen and Ladies:

         You have requested our opinion,  as counsel for  Immunomedics,  Inc., a
Delaware  corporation  (the  "Company"),  in  connection  with the  Registration
Statement on Form S-3 (the "Registration Statement") under the Securities Act of
1933  (the  "Act"),  filed by the  Company  with  the  Securities  and  Exchange
Commission (the "Commission").

         The Registration  Statement  relates to the offering by certain selling
stockholder of up to 17,828,532  shares (the  "Shares") of the Company's  common
stock,  $.01 par value per share (the  "Common  Stock"),  issuable  from time to
time,  upon  conversion  of the  remaining  outstanding  shares of the Company's
Series F Convertible Preferred Stock (the "Series F Stock").

         In the  preparation  of our opinion,  we have examined (1) the Restated
Certificate of Incorporation of the Company, as amended to date, (2) the By-Laws
of the  Company,  in effect on the date  hereof,  (3) minutes of meetings of the
Company's Board of Directors,  as made available to us by executive  officers of
the Company, (4) a certificate from an executive officer of the Company, (5) the
Registration  Statement,  (6) the  Securities  Purchase  Agreement,  dated as of
December  9, 1998 (the  Agreement"),  including  the  exhibits  incorporated  by
reference  therein  and  (7)  the  Waiver,   dated  October  11,  1999.  In  our
examinations,   we  have  assumed  the  genuineness  of  all   signatures,   the
authenticity  of all documents  submitted to us as originals,  the conformity to
the originals of all  documents  submitted to us as  certified,  photostatic  or
conformed  copies,  and the  authenticity  of the  originals  of all such latter
documents.

         Based upon such  examination,  we are of the  opinion  that the Shares,
when issued and delivered in accordance with the terms of the Agreement, and the
Certificate of Designations,  Preferences and Rights of the Series F Stock, will
be validly issued, fully paid and non-assessable.

         We hereby  consent  to the  filing of our  opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" in the prospectus included in the Registration Statement.

         Certain  partners of our Firm  beneficially  own 1,200 shares of Common
Stock.



                                                     Sincerely yours,

                                                     /s/ Warshaw Burstein Cohen
                                                       Schlesinger & Kuh, LLP


MDS/HMC

                                       E-1
<PAGE>



                                                                    EXHIBIT 23.1


                       CONSENT OF INDEPENDENT ACCOUNTANTS

The Board of Directors
Immunomedics, Inc.

We consent to the use of our report  incorporated herein by reference and to the
reference to our firm under the heading "Experts" in the Prospectus.


                                                                        KPMG LLP



Short Hills, New Jersey
November 9, 1999

                                       E-2
<PAGE>


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