<PAGE>
 
Exhibit 11.1 (a)


                Renal Treatment Centers, Inc. and Subsidiaries
          COMPUTATION OF PRIMARY AND FULLY DILUTED EARNINGS PER SHARE
                     for the year ended December 31, 1995


<TABLE>
<CAPTION>
                                                                       Primary          Fully Diluted
                                                                        1995                1995
                                                                        ----                ----     
<S>                                                                  <C>                <C>
Net income                                                           $14,630,804          $14,630,804
Add back interest on Denver earn out note, tax effected                      ---              283,136
------------------------------------------------------------------------------------------------------------------
Net income available to common stockholders                          $14,630,804          $14,913,940
==================================================================================================================
Weighted average number of shares outstanding                         21,868,067           21,868,067
                                                                                 
Weighted average number of maximum shares subject                                
  to exercise under outstanding stock options                          1,444,812            1,444,812
                                                                                 
Weighted average shares assumed issued upon                                      
  conversion of earn out note                                                ---              682,402
------------------------------------------------------------------------------------------------------------------
                                                                      23,312,879           23,995,281
Less treasury shares assumed purchased with proceeds                             
  from assumed exercise of outstanding common stock options              900,146              594,196
------------------------------------------------------------------------------------------------------------------
Weighted average number of common and common                                     
  stock equivalents outstanding                                       22,412,733           23,401,085
------------------------------------------------------------------------------------------------------------------
Net income per common and common stock equivalent                          $0.65                $0.64
==================================================================================================================
</TABLE>
<PAGE>
 
 Exhibit 11.1 (b)
 

                Renal Treatment Centers, Inc. and Subsidiaries
          COMPUTATION OF PRIMARY AND FULLY DILUTED EARNINGS PER SHARE
                     for the year ended December 31, 1996

<TABLE>
<CAPTION>
                                                                       Primary          Fully Diluted
                                                                        1996                1996
                                                                        ----                ----      
<S>                                                                  <C>                <C>
Net income                                                           $19,290,265          $19,290,265
Add back interest on Denver earn out note, tax effected                      ---              236,787
------------------------------------------------------------------------------------------------------------------
Net income available to common stockholders                          $19,290,265          $19,527,052
==================================================================================================================
Weighted average number of shares outstanding                         24,230,156           24,230,156
                                                                                   
Weighted average number of maximum shares subject                                  
  to exercise under outstanding stock options                          1,636,300            1,636,300
                                                                                   
Weighted average shares assumed issued upon                                        
  conversion of earn out note                                                ---              557,719
------------------------------------------------------------------------------------------------------------------
                                                                      25,866,456           26,424,175
Less treasury shares assumed purchased with proceeds                               
  from assumed exercise of outstanding common stock options              798,556              770,311
------------------------------------------------------------------------------------------------------------------
Weighted average number of common and common                                       
  stock equivalents outstanding                                       25,067,900           25,653,864
------------------------------------------------------------------------------------------------------------------
Net income per common and common stock equivalent                          $0.77                $0.76
==================================================================================================================
</TABLE>

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