Lock-Up Agreement


    Exhibit
      10.1

    


    


    GTC
      Biotherapeutics, Inc.

    175
      Crossing Boulevard

    Framingham,
      MA 01702

    


     

    [Executive
      Officer]

    c/o
      GTC
      Biotherapeutics, Inc. 

    175
      Crossing Boulevard

    Framingham,
      MA 01702

     

    Dear
      [          ]:

     

    This
      letter agreement (this “Agreement”)
      is
      being entered into between you and GTC Biotherapeutics, Inc. (the “Company”),
      a
      Massachusetts corporation, in connection with certain stock options granted
      to
      you pursuant to the Company’s 1993 and 2002 Equity Incentive Plans that are
“Underwater Options”, as defined below.

     

    1.    
      Background. 
       On December 22, 2005, the Compensation Committee of the Board of Directors
      of the Company determined to fully accelerate the vesting of each otherwise
      unvested stock option held by an option holder employed by the Company as of
      December __, 2005 if such option had an exercise price that is greater than
      or equal to $3.75 per share (each an “Underwater
      Option”).

     

    In
      the
      case of Underwater Options held by any employee who is an “executive officer” of
      the Company for purposes of Section 16 of the Securities Exchange Act of 1934
      (“an executive
      officer”),
      as
      you are, the Compensation Committee conditioned such acceleration of vesting
      on
      a requirement that before exercising any of the accelerated options the
      executive officer sign and deliver an agreement pursuant to which he or she
      agrees to refrain from selling, transferring, pledging, or otherwise disposing
      of any shares acquired upon the exercise of options so accelerated (other than
      shares required to satisfy minimum withholding taxes) until the earliest of
      :

     

    
      	·  	
              the
                date on which the exercise would have been permitted under the accelerated
                options’ pre-acceleration vesting
                terms;

            


    

    
      	·  	
              the
                day after the executive officer’s last day of employment with the Company;
                or

            


    

    
      	·  	
              the
                occurrence of a “change in control” of the Company as defined in any
                agreement between the Company and the executive officer, but only
                to the
                extent the accelerated options, absent this acceleration, would have
                otherwise been accelerated under the terms of such an
                agreement.

            


    

     

    The
      earliest of the foregoing dates that occurs shall be referred to herein as
      the
“Release
      Date.” 
      This Agreement is presented for your signature in order to satisfy this
      condition to your ability to exercise the portion of your Underwater Options
      that have been accelerated.

     

    2.    
      Lock-up
      Agreement.  In
      consideration of the acceleration of the vesting of your Underwater Options,
      you
      agree to refrain from selling, transferring, pledging, or otherwise disposing
      of
      any shares acquired upon the exercise of an accelerated Underwater Option of
      yours (other than shares required to satisfy minimum withholding taxes) until
      the Release Date applicable to such shares.

     

    3.    
      Counterparts.
           This Agreement may be executed in one or more
      counterparts, each of which shall be deemed to be an original but all of which
      together will constitute one in the same instrument.

     

    
      
         

        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    If
      this
      Agreement correctly sets forth our agreement on the subject matter hereof,
      please confirm your agreement by signing and returning the enclosed copy of
      this
      Agreement to the Company.

     

    
      	
               Dated:
                

            	
              Sincerely,

            
	
               

            	
               

            
	
               

            	
              GTC
                BIOTHERAPEUTICS, INC.

            
	
               

            	
               

            
	
               

            	
               

            
	
               

            	
              By:

            	
               

            	
               

            
	
               

            	
              Title:

            


    

     

    I
      acknowledge receipt and agree with the foregoing terms and
      conditions.

     

     

    
      	
               

            	
               

            
	
              Name:
                [                                                            ]