<PAGE>
                                                                    EXHIBIT 11.1
 
                       HEALTH SYSTEMS DESIGN CORPORATION
 
                   COMPUTATION OF NET INCOME (LOSS) PER SHARE
 
                    (In thousands, except per-share amounts)
 
<TABLE>
<CAPTION>
                                                        THREE MONTHS ENDED      SIX MONTHS ENDED
                                                            MARCH 31,              MARCH 31,
                                                      ----------------------  --------------------
                                                        1999         1998       1999       1998
                                                      ---------    ---------  ---------  ---------
<S>                                                   <C>          <C>        <C>        <C>
Net income (loss).................................    $     227    $    (398) $  (1,199) $  (1,552)
                                                      ---------    ---------  ---------  ---------
                                                      ---------    ---------  ---------  ---------
Weighted average common shares outstanding:
  Basic...........................................        6,704        6,545      6,690      6,540
                                                      ---------    ---------  ---------  ---------
                                                      ---------    ---------  ---------  ---------
  Fully Diluted...................................        6,754        6,545      6,690      6,540
                                                      ---------    ---------  ---------  ---------
                                                      ---------    ---------  ---------  ---------
Net income (loss) per common share:
  Basic...........................................    $    0.03    $   (0.06) $   (0.18) $   (0.24)
                                                      ---------    ---------  ---------  ---------
                                                      ---------    ---------  ---------  ---------
  Diluted.........................................    $    0.03    $   (0.06) $   (0.18) $   (0.24)
                                                      ---------    ---------  ---------  ---------
                                                      ---------    ---------  ---------  ---------
</TABLE>
 
Net Income (Loss) Per Common Share:
 
    Basic net income (loss) per common share (Basic EPS) excludes dilution and
is computed by dividing net income (loss) by the weighted average number of
common shares outstanding during the period. Diluted net income per common share
(Diluted EPS) reflects the potential dilution that could occur if stock options
or other contracts to issue common stock were exercised or converted into common
stock. The computation of Diluted EPS does not assume exercise or conversion of
securities that would have an antidilutive effect on net income per common
share. In periods where losses are recorded, common stock equivalents would
decrease the loss per share and are therefore not added to the weighted average
shares outstanding.
 
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