<PAGE>   1

                                                                     EXHIBIT 11
                                                                    PAGE 1 OF 2

                  UNION PLANTERS CORPORATION AND SUBSIDIARIES
                COMPUTATION OF PRIMARY EARNINGS PER COMMON SHARE



<TABLE>
<CAPTION>
                                                         THREE MONTHS ENDED
                                                             MARCH 31,
                                                  ------------------------------
                                                      1997               1996
                                                  ------------      ------------
                                                     (DOLLARS IN THOUSANDS,
                                                     EXCEPT PER SHARE DATA)
<S>                                               <C>               <C>         
     PRIMARY EARNINGS PER COMMON SHARE

     Average shares outstanding                     65,361,121        62,848,176
     Assumed exercise of options outstanding         1,402,109         1,234,486
                                                  ------------      ------------
     Primary average shares outstanding             66,763,230        64,082,662
                                                  ============      ============

     Net earnings                                 $     59,192      $     47,152
     Less: Preferred stock dividends
           Series B                                         --               (88)
           Series E                                     (1,496)           (1,748)
                                                  ------------      ------------
     Net earnings applicable to common shares     $     57,696      $     45,316
                                                  ============      ============

     Primary net earnings per common share        $        .86      $        .70
                                                  ============      ============
</TABLE>








<PAGE>   2



                                                                     EXHIBIT 11
                                                                    PAGE 2 OF 2



                  UNION PLANTERS CORPORATION AND SUBSIDIARIES
             COMPUTATION OF FULLY DILUTED EARNINGS PER COMMON SHARE



<TABLE>
<CAPTION>
                                                       THREE MONTHS ENDED
                                                             MARCH 31,
                                                  ------------------------------
                                                      1997              1996
                                                  ------------      ------------
                                                       (DOLLARS IN THOUSANDS,
                                                       EXCEPT PER SHARE DATA)
<S>                                               <C>               <C>         
FULLY DILUTED EARNINGS PER COMMON SHARE

Average shares outstanding                          65,361,121        62,848,176
Assumed exercise of options outstanding              1,402,808         1,286,700
Assumed conversion of preferred stock outstanding:
    Series B                                                --           339,768
    Series E                                         4,060,006         4,370,524
                                                  ------------      ------------
Fully diluted average shares outstanding            70,823,935        68,845,168
                                                  ============      ============

Net earnings                                      $     59,192      $     47,152
Less: Preferred stock dividends                             --                --
                                                  ------------      ------------
Net earnings applicable to common shares          $     59,192      $     47,152
                                                  ============      ============

Fully diluted net earnings per common share       $        .84      $        .68
                                                  ============      ============
</TABLE>