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                         Transkaryotic Therapies, Inc.

<TABLE>
                                                    Exhibit 11
<CAPTION>
                                                               Three Months Ended                       Six Months Ended
                                                       June 30, 1997       June 30, 1996        June 30, 1997        June 30, 1996
                                                       -------------       -------------        -------------        -------------

<S>                                                      <C>                 <C>                  <C>                  <C>         
Weighted average common shares outstanding               16,666,898           5,197,040           16,653,916            5,197,007
                                                                                                                   
Effect of preferred stock - assumed converted                                                                      
   at date of issuance                                            -           5,776,819                    -            5,776,819
                                                                                                                   
Weighted average common stock equivalent shares                                                                    
   resulting from stock options and warrants              1,298,403                   -                    -                    -
                                                                                                                   
Effect of common and common stock equivalent                                                                       
   shares issued by the Company during the twelve                                                                  
   month period immediately preceding the Company's                                                                
   initial public offering in October 1996 (using the                                                              
   treasury stock method)                                         -           3,281,510                    -            3,281,510
                                                        -----------         -----------          -----------          -----------

Shares used to compute net loss per share                17,965,301          14,255,369           16,653,916           14,255,336
                                                        ===========         ===========          ===========          ===========

Net income (loss)                                       $   326,456         $(4,617,721)         $(3,466,998)         $(5,987,344)
                                                        ===========         ===========          ===========          ===========

Net income (loss) per share (pro forma in 1996)         $      0.02         $     (0.32)         $     (0.21)         $     (0.42)
                                                        ===========         ===========          ===========          ===========
</TABLE>



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