Exhibit 10.4

                                                                                         Exhibit
    10.4

     

    IMMUNOGEN,
      INC.

    2004
      NON-EMPLOYEE
      DIRECTOR COMPENSATION 

    AND
      DEFERRED SHARE
      UNIT PLAN

    (as
      amended on
      September 5, 2006)

     

    


     

    WHEREAS,
      ImmunoGen, Inc. (the
“Company”) has previously established plans or arrangements pursuant to which
      Non-Employee Directors of the Company have been compensated for their services
      as directors of the Company;

     

    WHEREAS,
      the Board of Directors of
      ImmunoGen, Inc. (the “Board”) wishes to align director compensation more
      directly with the shareholders' interest;

     

    WHEREAS,
      the Board has determined
      that it is in the interest of the shareholders to establish a new compensation
      package that will provide for payment and future annual accruals to the
      Non-Employee Directors;

     

    WHEREAS,
      the Board has determined
      that it is in the interest of shareholders to allow Non-Employee Directors
      to
      defer their fees into an account hereunder;

     

    WHEREAS,
      the Board has determined
      the terms and conditions of the ImmunoGen, Inc. 2004 Non-Employee Director
      Compensation and Deferred Share Unit Plan (the “Plan”) and wishes to formally
      establish the Plan effective July 1, 2004;

     

    WHEREAS,
      on September 5, 2006 the
      Board has determined to make changes to certain of the terms and conditions
      of
      the Plan; 

     

    NOW,
      THEREFORE,
      the Company through this
      instrument establishes the ImmunoGen, Inc. 2004 Non-Employee Director
      Compensation and Deferred Share Unit Plan, as amended, as follows:

     

     

    
      	
              Section
                1

            	
              Interpretation

            


    

     

    
      	
              1.1

            	
              Purposes

            


    

     

    The
      purposes of the Plan are:

     

    
      	 	
              (a)

            	
              to
                compensate Non-Employee Directors for their services to the
                Company;

            


    

     

    
      	 	
              (b)

            	
              to
                facilitate holdings of Deferred Share Units by the Company’s Non-Employee
                Directors and thereby align their interests more closely with those
                of the
                Company’s shareholders; and

            


    

     

    
      	 	
              (c)

            	
              to
                provide a financial incentive that will help the Company to attract
                and
                retain highly qualified individuals to serve as Non-Employee Directors
                of
                the Company. 

            


    

     

    
      	
              1.2

            	
              Definitions

            


    

     

    Wherever
      used in the Plan, unless otherwise defined, the following terms shall have
      the
      meanings set forth below: 

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    (a) “Affiliate”
      means a subsidiary,
      division or affiliate of the Company, as determined in accordance with Section
      414(b), (c) or (m) of the Code;

     

    
      	 	
              (b)

            	
              “Annual
                Deferred Share Unit Retainer”
has
                the meaning
                set forth in Section 3.1; 

            


    

     

    
      	 	
              (c)

            	
              “Annual
                Director Fees” has
                the meaning set
                forth in Section 3.2;

            


    

     

    
      	 	
              (d)

            	
              “Beneficiary”
                has the meaning set
                forth in Section 2.5; 

            


    

     

    
      	 	
              (e)

            	
              “Board”
                or“Board
                of
                Directors”
                means those
                individuals who serve from time to time as the Board of Directors
                of the
                Company; 

            


    

     

    
      	 	
              (f)

            	
              “Code”
                means
                the United
                States Internal Revenue Code of 1986, as
                amended;

            


    

     

    
      	 	
              (g)

            	
              “Commencement
                Date” has
                the meaning set
                forth in Section 1.3;

            


    

     

    
      	 	
              (h)

            	
              “Committee”
                means the committee
                of the Board of Directors to which the Board of Directors has delegated
                power to act under or pursuant to the provisions of the Plan, initially
                the Compensation Committee of the
                Board;

            


    

     

    
      	 	
              (i)

            	
              “Common
                Stock”
                means shares of the
                Company’s common stock, $.01 par value per
                share;

            


    

     

    
      	 	
              (j)

            	
              “Company”
                means ImmunoGen,
                Inc., a Massachusetts corporation;

            


    

     

    
      	 	
              (k)

            	
              “Deferred
                Share Unit” means
                a unit
                credited by the Company to a Non-Employee Director by way of a bookkeeping
                entry in the books of the Company, the value of which at any particular
                date shall be the Fair Market Value at that
                date;

            


    

     

    
      	 	
              (l)

            	
              “DSU
                Account”
                has the meaning set
                forth in Section 2.2;

            


    

     

    
      	 	
              (m)

            	
              “Effective
                Date” has
                the meaning set
                forth in Section 1.3;

            


    

     

    
      	 	
              (n)

            	
              “Election
                Form”
                means a document
                substantially in the form attached as Schedule “A” hereto, as such form
                may be amended or revised from time to
                time;

            


    

     

    
      	 	
              (o)

            	
              “Fair
                Market
                Value”
                means:

            


    

     

    (1) If
      the Common Stock is
      listed on a national securities exchange or traded in the over-the-counter
      market and sales prices are regularly reported for the Common Stock, the closing
      or last price of the Common Stock on the Composite Tape or other comparable
      reporting system for the trading day on the applicable date which
      is the date of
      grant, and if such applicable date is not a trading day, the last market trading
      day prior to such date;

     

    (2) If
      the Common Stock is not
      traded on a national securities exchange but is traded on the over-the-counter
      market, if sales prices are not regularly reported for the Common Stock for
      the
      trading day referred to in clause (1), and if bid and asked prices for the
      Common Stock are regularly reported, the mean between the bid and the asked
      price for the Common Stock at the close of trading in the over-the-counter
      market for the trading day on which Common Stock was traded on the
      applicable
      date which
      is
      the date of grant,
      and if such applicable date is not a trading day, the last market trading day
      prior to such date;
      and


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    


        (3)If
      the Common Stock is
      neither listed on a national securities exchange nor traded in the
      over-the-counter market, such value as the Committee, in good faith, shall
      determine with respect to any particular date;

     

    
      	 	
              (p)

            	
              “First
                Year”
                means
                the first 12
                month period during which an individual first serves as a Non-Employee
                Director of the Company commencing after the Commencement Date of
                the
                Plan. Only individuals elected to serve on the Board who are within
                their
                first twelve months of service on or after the Commencement Date
                shall be
                eligible for First Year credits to their DSU Account under this
                Plan;

            


    

     

    
      	 	
              (q)

            	
              “Fiscal
                Year” means
                the twelve
                month period beginning on July 1 and ending on June 30 of any
                year;

            


    

     

    
      	 	
              (r)

            	
              “Lead
                Director” means
                a Non-Employee
                Director appointed by the Board to such
                position;

            


    

     

    
      	 	
              (s)

            	
              “Lead
                Director Fees” has
                the meaning set
                forth in Section 3.2; 

            


    

     

    
      	 	
              (t)

            	
              “Non-Employee
                Director”
                means a member of
                the Board of Directors who is not an employee of the Company or any
                Affiliate of the Company; 

            


    

     

    
      	 	
              (u)

            	
              “Plan”
                means this
                ImmunoGen, Inc. 2004 Non-Employee Director Compensation and Deferred
                Share
                Unit Plan, as amended and restated from time to time;
                

            


    

     

    
      	 	
              (v)

            	
              “Plan
                Year”
                means the twelve
                month period beginning on July 1 and ending on June 30 of any
                year;

            


    

     

    
      	 	
              (w)

            	
              “Quarter”
                means a fiscal
                quarter of the Company which, until changed by the Company, shall
                be the
                three-month periods ending September 30, December 31, March 31 and
                June 30
                in any calendar year; 

            


    

     

    
      	 	
              (x)

            	
              “Redemption
                Amount”
                has the meaning set
                forth in Section 4.1; 

            


    

     

    
      	 	
              (y)

            	
              “Redemption
                Date”
                has the meaning set
                forth in Section 4.1; 

            


    

     

    
      	 	
              (z)

            	
              “Second
                Year” means
                that Plan
                Year, or portion thereof, commencing upon the first anniversary of
                appointment of a Non-Employee Director and ending on the last day
                of the
                Plan Year in which such anniversary occurs. Only individuals eligible
                to
                receive First Year credits to their DSU Account under this Plan shall
                be
                eligible to receive Second Year credits to their DSU Account under
                this
                Plan provided however, that any individual who first became a Non-Employee
                Director in 2004, shall be entitled to receive Second Year credits
                even if
                First Year credits were not
                received;

            


    

     

    
      	 	
              (aa)

            	
              “Termination
                Date”
                means, with respect
                to a Non-Employee Director, the date upon which such Non-Employee
                Director
                ceases to be a member of the Board for any reason whatsoever,
                including death or
                disability;
                and
                

            


    

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    
      	 	
              (bb)

            	
              “Termination
                Value”
                means the Fair
                Market Value of the Common Stock on the Termination Date.
                

            


    

     

    1.3 Commencement
      Date
      and Effective Date 

     

    The
      Plan
      was initially adopted effective as of July 1, 2004 (the “Commencement Date”).
      The Plan, as amended, shall be effective on November 15, 2006 (the “Effective
      Date”). 

     

    1.4 Eligibility

     

    Each
      Non-Employee Director shall be eligible to participate in the Plan.


     

    1.5 Construction

     

    All
      references in the Plan to the masculine shall also include the feminine and
      all
      references to the singular shall also include the plural and vice versa, as
      the
      context shall require. If any provision of the Plan is determined to be illegal
      or invalid for any reason, in whole or in part, such illegality or invalidity
      shall not affect the remaining parts of the Plan and the Plan shall be construed
      and enforced as if the illegal or invalid provision had not been included.
      Headings wherever used herein are for reference purposes only and do not limit
      or extend the meaning of the provisions contained herein. A reference to a
      “Section” means a section of the Plan, unless expressly stated otherwise.


     

    1.6 Governing
      Law

     

    The
      Plan
      shall be governed by and construed in accordance with the laws of The
      Commonwealth of Massachusetts. 

     

     

    
      	
              Section
                2

            	
              Administration
                of the Plan

            


    

     

    2.1 Administration

     

    The
      Committee shall have complete discretionary authority and power to (i) construe,
      interpret and administer the Plan and any agreement or instrument entered into
      under the Plan, (ii) establish, amend and rescind any rules and regulations
      relating to the Plan, (iii) make any other determinations that the
      Committee deems necessary or desirable for the administration of the Plan,
      including without limitation decisions regarding eligibility to participate
      and
      the amount and value of any payment, and (iv) delegate to other persons any
      duties and responsibilities relating to the administration of the Plan. The
      Committee may correct any defect or supply any omission or reconcile any
      inconsistency or ambiguity in the Plan in the manner and to the extent the
      Committee deems, in its sole and absolute discretion, necessary or desirable.
      No
      member of the Committee shall be liable for any action or determination made
      in
      good faith. Any decision of the Committee with respect to the administration
      and
      interpretation of the Plan shall be binding and conclusive for all purposes
      and
      on all persons, including the Company, all Non-Employee Directors and any other
      person claiming an entitlement or benefit through any Non-Employee Director.
      All
      expenses of administration of the Plan shall be borne by the Company.


     

    2.2 DSU
      Accounts

     

    The
      Company shall maintain in its books and records an account for each Non-Employee
      Director (a “DSU Account”) recording at all times the number of Deferred Share
      Units credited to a Non-Employee Director. Upon payment in satisfaction of
      Deferred Share Units credited to a Non-Employee

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    Director in
      the
      manner described herein, such Deferred Share Units shall be cancelled. After
      the
      end of each Quarter, the Company shall provide each Non-Employee Director with
      a
      written statement showing the balance in such Non-Employee Director’s DSU
      Account as at the end of the applicable Quarter.

     

    2.3 Credit
      for
      Dividends on Deferred Share Units

     

    When
      and
      if cash dividends are paid on the Common Stock of the Company, a Non-Employee
      Director’s DSU Account shall be credited with dividend equivalents in the form
      of additional Deferred Share Units. Such dividend equivalents shall be credited
      on the dividend payment date and shall be computed by dividing (a) the amount
      obtained by multiplying the amount of the dividend declared and paid per share
      of Common Stock by the number of Deferred Share Units credited to the
      Non-Employee Director’s DSU Account on the record date for the payment of such
      dividend, by (b) the Fair Market Value of the Common Stock on the dividend
      payment date for such dividend, with fractions of Deferred Share Units so
      credited computed to four decimal points rounded down. 

     

    2.4 Share
      Adjustments
      and Reorganizations

     

    If
      (a)
      there is any stock split, stock consolidation, reclassification,
      recapitalization or similar event affecting the Common Stock, (b) the Common
      Stock is exchanged in connection with a reorganization, including any merger,
      amalgamation, consolidation of the Company or similar event, or a sale by the
      Company of all or substantially all of its assets, for a different number or
      class of shares or other securities of the Company or for shares or other
      securities of any other Company, (c) new, different or additional shares or
      other securities of the Company or of another company are received by holders
      of
      the Common Stock, or (d) any distribution is made to the holders of Common
      Stock
      (other than a cash dividend), then the Committee shall make such adjustments
      to
      the Deferred Share Units credited to the Non-Employee Directors under the Plan
      as the Committee deems appropriate in its sole discretion. Except as provided
      above, the issuance by the Company of any shares of the Company, or any rights,
      warrants, options or other securities convertible into or exchangeable for
      any
      shares of the Company, shall not affect the number of Deferred Share Units
      credited pursuant to the terms of the Plan. 

     

    2.5 Designation
      of
      Beneficiary

     

    Upon
      his
      election or appointment to the Board, subject to applicable law, each
      Non-Employee Director shall designate an individual as his beneficiary to
      receive any benefits that are payable under the Plan upon the death of such
      Non-Employee Director (the “Beneficiary”). The Non-Employee Director may,
      subject to applicable laws, change his Beneficiary at any time or from time
      to
      time. Where no Beneficiary has been validly designated by the Non-Employee
      Director, or the Beneficiary does not survive the Non-Employee Director, the
      Non-Employee Director’s legal representative shall be his Beneficiary. In the
      event of a Non-Employee Director’s death, the Beneficiary shall be entitled to
      exercise the rights of, and receive the benefits payable to, the Non-Employee
      Director under Section 5. 

     

     

    
      	
              Section
                3

            	
              Compensation

            


    

     

    3.1 Annual
      Deferred
      Share Unit Retainers 

     

    (a) Subject
      to the other
      provisions of this Plan, for each Plan Year beginning with the Commencement
      Date, each Non-Employee Director shall have credited to his DSU Account as
      of
      the first day his participation in the Plan commences during a Plan Year an
      amount determined in accordance with this Section 3.1(a) as an Annual Deferred
      Share Unit Retainer for his services to the Board. Any

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    fractional
      Deferred Share Unit shall be calculated to four decimal points rounded down.
      All
      amounts credited may be subject to such conditions as may be imposed by the
      Committee at the time it is credited. From the Commencement Date until the
      Effective Date, the following shall be credited for Non-Employee Directors
      as an
      Annual Deferred Share Unit Retainer: 

     

    (i) For
      the First Year there
      shall be credited for each new Non-Employee Director Deferred Share Units to
      his
      DSU Account. The dollar value of such Deferred Share Units will be established
      from time to time by the Committee.

     

    (ii) For
      the Second Year there
      shall be credited for each new Non-Employee Director who received a First Year
      credit in accordance with the foregoing Deferred Share Units to his DSU Account,
      which amount shall be pro rated based upon the number of whole months remaining
      between the beginning of the Second Year and the end of the Plan Year in which
      such Second Year falls. The dollar value of such Deferred Share Units will
      be
      established from time to time by the Committee.

     

    (iii) For
      existing directors,
      during each Plan Year, there shall be credited Deferred Share Units to their
      respective DSU Accounts. The dollar value of such Deferred Share Units will
      be
      established from time to time by the Committee. Unless otherwise provided by
      the
      Committee, the Annual Deferred Share Unit Retainer credited herein shall be
      pro
      rated to reflect the actual number of whole months that the Non-Employee
      Director has served on the Board during the Plan Year in which such amount
      is
      credited. 

     

    (iv) Non-Employee
      Directors
      shall receive an Annual Deferred Share Unit Retainer for any Plan Year only
      under one of either (i), (ii) or (iii) above; that is, a Non-Employee Director
      receiving credits under (i) above during a Plan Year shall not be eligible
      for
      credits during that Plan Year under either (ii) or (iii) above.

     

    (v) All
      amounts credited as an
      Annual Deferred Share Unit Retainer in (i) (ii) or (iii) shall vest ratably
      in
      monthly increments at the end of each month after the amount is credited to
      the
      DSU Account. Any Non-Employee Director who ceases to be a member of the Board
      for any reason during a Plan Year shall forfeit any amount credited to the
      DSU
      Account that is not, as of the date of such Termination Date, vested in
      accordance with the terms herein.

     

    (b) Subject
      to the other
      provisions of this Plan, beginning with the Effective Date, each Non-Employee
      Director shall have credited to his DSU Account an amount determined in
      accordance with this Section 3.1(b) as an Annual Deferred Share Unit Retainer
      for his services to the Board. Any fractional Deferred Share Unit shall be
      calculated to four decimal points rounded down. All amounts credited may be
      subject to such conditions as may be imposed by the Committee at the time it
      is
      credited. As of the Effective Date, the following shall be credited for
      Non-Employee Directors as an Annual Deferred Share Unit Retainer: 

     

    (i) For
      each Non-Employee
      Director who was credited Deferred Share Units on July 1, 2006 and is a
      Non-Employee Director on the Effective Date, there shall be credited additional
      Deferred Share Units to his DSU Account on the Effective Date. The dollar value
      of such Deferred Share Units shall be $17,500. Each such Non-Employee Director
      shall be credited additional Deferred Share Units to his DSU Account on the
      earlier of November 20 of such year or the date of each annual meeting of
      stockholders occurring after the Effective Date. The dollar value of such
      Deferred Share Units shall be $30,000 or such other amount as may be determined
      by the Committee from time to time (the “Continuing Retainer”).

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    (ii) For
      each Non-Employee
      Director who becomes a Non-Employee Director for the first time on or after
      November 14, 2006, there shall be credited Deferred Share Units to his DSU
      Account on the later of the Effective Date or the date the Non-Employee Director
      is first appointed or elected to the Board. The dollar value of such Deferred
      Share Units shall be $65,000 or such other amount as may be determined by the
      Committee from time to time (the “Initial Retainer”). On the date that is one
      year from the date of the payment of the Initial Retainer, each such
      Non-Employee Director who continues to be a Non-Employee Director shall be
      credited additional Non-Employee Director Deferred Share Units to his DSU
      account. The amount to be credited shall be the Continuing Retainer pro rated
      based upon the number of whole months remaining between the date of payment
      and
      the last day of the following October. From and after that date each such
      Non-Employee Director shall be credited additional Deferred Share Units to
      his
      DSU Account on the earlier of November 20 of such year or the date of each
      annual meeting of stockholders. The dollar value of such Deferred Share Units
      shall be the Continuing Retainer. 

     

    (iii) All
      amounts credited as an
      Annual Deferred Share Unit Retainer in (i) and (ii) above shall vest ratably
      over a three year period in quarterly increments at the end of each quarter
      after the amount is credited to the DSU Account. Any Non-Employee Director
      who
      ceases to be a member of the Board for any reason shall forfeit any amount
      credited to the DSU Account that is not, as of the date of such Termination
      Date, vested in accordance with the terms herein.

     

    3.2 Annual
      Director
      Fees
      and Lead Director
      Fees

     

    Each
      Non-Employee Director
      shall be paid $25,000 per year, or such other amount as may be determined by
      the
      Committee from time to time, for attendance at meetings for each Fiscal Year
      (prorated for any partial Fiscal Year). The Lead Director shall be paid an
      additional $40,000 per year, or such other amount as may be determined by the
      Committee from time to time, for the services he performs to fulfill the duties
      of Lead Director. From and after the Effective Date, each Non-Employee Director
      shall be paid $35,000 per year, or such other amount as may be determined by
      the
      Committee from time to time, for attendance at meetings for each Fiscal Year
      (prorated for any partial Fiscal Year) and the Lead Director shall be paid
      an
      additional $30,000 per year, or such other amount as may be determined by the
      Committee from time to time, for the services he performs to fulfill the duties
      of Lead Director. In addition, commencing on the Effective Date, chairpersons
      of
      the Audit, Compensation, and Nominating and Governance Committees shall be
      paid
      $15,000, $9,000 and $9,000 per year, respectively, and each member of the Audit,
      Compensation, and Nominating and Governance Committee, other than the
      chairpersons, shall be paid $8,000, $5,000 and $5,000 per year, respectively,
      or
      such other amount as may be determined by the Committee from time to time,
      for
      attendance at committee meetings for each Fiscal Year (prorated for any partial
      Fiscal Year). One-fourth of such payments shall be made to each Non-Employee
      Director and the Lead Director quarterly for each quarter in which he remains
      a
      Non-Employee Director, in arrears. In addition, each Non-Employee Director
      shall
      be compensated for their reasonable expenses incurred for attending meetings
      and
      otherwise acting on the Company’s behalf. Each Non-Employee Director shall have
      the right to elect to defer any part or all of the Annual Director Fees and
      Lead
      Director Fees described herein in the form of Deferred Share Units in an amount
      equal to the Fair Market Value of Deferred Share Units equal to the amount
      of
      cash deferred. Such Deferred Share Units shall be fully vested upon being
      credited to the individual’s DSU Account and the Non-Employee Director’s
      entitlement to the redemption of such Deferred Share Units shall be governed
      by
      the terms of this Plan.

     


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    3.3 Timing
      of
      Election

     

    Each
      Non-Employee Director
      shall, if he chooses to defer Annual
      Director Fees in
      accordance with Section 3.2 above, within 30 days following either the
      Commencement Date, or his first election or appointment to the Board, if later,
      in respect of amounts payable during the remainder of such calendar year, and
      thereafter by December 31 in respect of amounts payable on or after January
      1 of
      the next calendar year, complete, sign and deliver an Election Form to the
      Treasurer of the Company indicating his election for the following calendar
      year. If no timely election has been made, then the individual shall be deemed
      to have elected to receive his Annual Director Fees in cash. Notwithstanding
      the
      foregoing, an election (or non-election) made pursuant to this Section 3.3
      shall
      remain in effect for subsequent calendar years until it is changed by the
      completion, signature and delivery to the Treasurer of the Company of a new
      Election Form, in accordance with the terms of the Plan. 

     

     

    
      	
              Section
                4

            	
              Redemption
                of DSUs

            


    

     

    4.1 Redemption
      Process

     

    Upon
      any
      termination of a Non-Employee Director, the Company shall redeem all fully
      vested Deferred Share Units credited to the DSU Account of such Non-Employee
      Director. The Company shall pay the relevant Non-Employee Director within five
      business days of the Termination Date (the “Redemption Date”) the amount (the
“Redemption Amount”) which shall be obtained by multiplying (a) the number of
      Deferred Share Units to be redeemed by (b) the Termination Value, less any
      applicable withholding or similar taxes, and shall be fully discharged in so
      doing and such Deferred Share Units shall, as provided for in Section 2.2,
      be
      cancelled. The Redemption Amount shall be paid by check; provided, however
      if
      the Company’s proposed 2006 Employee, Director and Consultant Equity Plan (the
“Stock Plan”) is approved by the Company’s stockholders and the termination is
      after the Effective Date then the Redemption Amount shall be paid in shares
      of
      Common Stock of the Company pursuant to the Company’s Stock Plan. 

     

     

    
      	
              Section
                5

            	
              General

            


    

     

    5.1 Unfunded
      Plan

     

    The
      Plan is designed to be
      an unfunded arrangement. It is specifically recognized by both the Company
      and
      any Non-Employee Director that this Plan is only a general corporate commitment
      and that each Participant must rely upon the general credit of the Company
      for
      the fulfillment of its obligations. Under all circumstances the rights of
      participants in this Plan to any asset held by the Company will be no greater
      than the rights expressed in this Plan. Nothing contained in this Plan will
      constitute a guarantee by the Company that the assets of the Company will be
      sufficient to pay any benefits under this Plan or would place the participant
      in
      a secured position ahead of general creditors of the Company. The Plan will
      not
      create any lien, claim, encumbrance, right, title or other interest of any
      kind
      whatsoever in any participant in any asset held by the Company. No specific
      assets of the Company have been or will be set aside, or will in any way be
      transferred to any trust or will be pledged in any way for the performance
      of
      the Company’s obligations under this Plan which would remove those assets from
      being subject to the general creditors of the Company.


    
      
         

        


        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    5.2 Successors
      and
      Assigns

     

    The
      Plan shall be binding
      on the Company and its successors and assigns and each Non-Employee Director
      and
      his heirs and legal representatives and on any receiver or trustee in bankruptcy
      or representative of creditors of the Company or Non-Employee Director, as
      the
      case may be.

     

    5.3 Amendment
      or
      Termination of the Plan

     

    The
      Board may amend or
      terminate the Plan at any time as it deems necessary or appropriate, but no
      such
      amendment or termination shall, without the consent of the Non-Employee Director
      or unless required by law, adversely affect the rights of a Non-Employee
      Director with respect to vested Deferred Share Units to which the Non-Employee
      Director is then entitled under the Plan. 

     

    If
      the Board terminates
      the Plan, no additional Deferred Share Units will be credited to the DSU Account
      of a Non-Employee Director after the effective date of such termination, but
      previously credited Deferred Share Units shall remain outstanding, be entitled
      to dividend equivalents as provided under the Plan, and be paid in accordance
      with the terms and conditions of the Plan existing at the time of termination.
      The Plan will finally terminate for all purposes when the last remaining
      Non-Employee Director receives payment of all Deferred Share Units which have
      been credited to his DSU Account.

     

    5.4 Applicable
      Trading
      Policies

     

    The
      Committee and each
      Non-Employee Director will ensure that all actions taken and decisions made
      by
      the Committee or the Non-Employee Director, as the case may be, pursuant to
      the
      Plan comply with all applicable laws, including securities and income tax laws,
      and all applicable policies, guidelines or similar requirements of the Company
      relating to conflicts of interest, business and ethical conduct.

     

    5.5 Limitations
      on Rights of
      Non-Employee Directors

     

    (a) Except
      as specifically set
      out in the Plan, no Non-Employee Director or any other person shall have any
      claim or right to any cash or other benefit in respect of Deferred Share Units
      credited pursuant to the Plan.

     

    (b) Any
      and all of the rights
      of the Non-Employee Directors respecting Deferred Share Units or other benefits
      under the Plan shall not be transferable or assignable other than by will or
      the
      laws of descent and distribution, nor shall they be pledged, encumbered or
      charged, and any attempt to do so shall be void.

     

    (c) Neither
      the Plan nor any
      award hereunder shall be construed as conferring upon a Non-Employee Director
      a
      right to be retained as a member of the Board or a claim or right to any future
      awards or other benefits under the Plan.

     

    (d) Under
      no circumstances
      shall Deferred Share Units be considered Common Stock of the Company nor shall
      they entitle any Non-Employee Director or other person to exercise any voting
      rights or any other rights attaching to the ownership of Common Stock, nor
      shall
      any Non-Employee Director or other person be considered the owner of Common
      Stock by virtue of this Plan.

     

    (e) Any
      liability of the
      Company to any Non-Employee Director with respect to receipt of Deferred Share
      Units shall be based solely upon contractual obligations created by the Plan.
      Neither the Committee nor the Board shall be liable for any actions taken in
      accordance with the terms of the Plan.

     

    5.6 Compliance
      with
      Law

     

    The
      obligations of the
      Company with respect to the delivery of Deferred Share Units pursuant to the
      terms of the Plan are subject to compliance with all applicable laws and
      regulations. In connection with the Plan, each Non-Employee Director shall
      comply with all applicable laws and regulations and shall furnish the Company
      with any and all information and undertakings as may be required to ensure
      compliance therewith.

     

    5.7 Applicable
      Taxes
      and Deductions

     

    The
      Company shall be
      authorized to deduct from any amount paid or credited hereunder such taxes
      and
      other amounts as may be required by applicable law or regulation in such manner
      as it determines appropriate.

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

    


     


    SCHEDULE
      A

    


    


    IMMUNOGEN,
      INC.

    2004
      NON-EMPLOYEE
      DIRECTOR COMPENSATION

    AND
      DEFERRED SHARE
      UNIT PLAN, as amended

    


     

    CALENDAR
      YEAR
      2007 INDIVIDUAL ELECTION FORM

     

    


    The
      undersigned hereby confirms that I have read, and agree to abide by, the terms
      of the ImmunoGen, Inc. 2004 Non-Employee Director Compensation and Deferred
      Share Unit Plan, as amended (the “Plan”). I understand that I am required to
      make annual elections in accordance with the terms of the Plan. In accordance
      with those terms, I make the following elections with respect to any
      compensation to be earned by me as a Non-Employee Director in calendar year
      2007: 

    


    Annual
      Director
      Fee Election.
      I may elect to receive
      all of such compensation in cash, Deferred Stock Units or a combination
      thereof.

    


    Accordingly,
      I elect to
      receive my Annual Director Fees as follows:

    


    
      	 	
              1.

            	
              ____
                % in
                Cash

            


    

    


    
      	 	
              2.

            	
              ____
                % in Deferred
                Stock Units 

            


    

    


    100
      %
      Total

    


    


    I
      understand that by electing Deferred Stock Units as described in the Plan,
      I
      have agreed to defer the payment of any proceeds from such Deferred Stock Units
      until such time as my services as a Non-Employee Director of ImmunoGen, Inc.
      are
      terminated and that the Deferred Stock Units shall remain part of the general
      assets of ImmunoGen, Inc. until I receive payment of the same. 

    


    
 

                              
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    Print
      Name 

    


                              
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