EXHIBIT 11
 
                        Peritus Software Services, Inc.
 
       Statement re Computation of Net Income (Loss) Per Common Share and
                  Pro Forma Net Income (Loss) Per Common Share
 
                                  (Unaudited)
 


                                    Three Months Ended     Nine Months Ended
                                      September 30,          September 30,
                                   --------------------  ----------------------
                                     1997*      1996       1997*       1996
                                   ---------- ---------  ---------- -----------
                                                        
Net income (loss), as reported...  $   84,000 $(206,000) $  928,000 $(5,383,000)
Preferred stock preference items:
  Accrual of cumulative dividends
   on Series A and Series B
   redeemable convertible
   preferred stock...............         --    182,000     675,000     385,000
  Accretion to redemption value
   of Series A and Series B
   redeemable convertible
   preferred stock...............         --     33,000         --       84,000
  Accretion to redemption value
   of redeemable common stock
   rights........................         --     20,000      57,000      41,000
                                   ---------- ---------  ---------- -----------
    Total preferred stock
     preference items............         --    235,000     732,000     520,000
                                   ---------- ---------  ---------- -----------
Net income (loss) attributable to
 common stockholders.............      84,000  (441,000)    196,000  (5,903,000)
                                   ========== =========  ========== ===========
Basic weighted average common
 stock outstanding...............  12,432,000 5,878,000   8,107,000   5,860,000
                                   ========== =========  ========== ===========
Basic net income (loss) per
 share...........................  $     0.01 $   (0.08) $     0.02 $     (1.01)
                                   ========== =========  ========== ===========
Diluted weighted average shares
 outstanding:
  a. shares attributable to
    common stock outstanding.....  12,432,000 5,878,000   8,107,000   5,860,000
  b. shares attributable to
    common stock options and
    warrants.....................   1,848,000       --    3,359,000         --
                                   ========== =========  ========== ===========
                                   14,280,000 5,878,000  11,466,000   5,860,000
                                   ========== =========  ========== ===========
Diluted net income (loss) per
 share...........................  $     0.01 $   (0.08) $     0.02 $     (1.01)
                                   ========== =========  ========== ===========
Net income (loss)................  $   84,000 $(206,000) $  928,000 $(5,383,000)
Pro forma basic weighted average
 shares outstanding:
  a. shares attributable to
    common stock outstanding.....  12,432,000 5,878,000   8,107,000   5,860,000
  b. shares attributable to
    redeemable convertible
    preferred stock..............         --  1,904,000   2,495,000   1,377,000
                                   ========== =========  ========== ===========
                                   12,432,000 7,782,000  10,602,000   7,237,000
                                   ========== =========  ========== ===========
Pro forma basic net income (loss)
 per share.......................  $     0.01 $   (0.03) $     0.09 $     (0.74)
                                   ========== =========  ========== ===========
Pro forma diluted weighted
 average shares outstanding:
  a. shares attributable to
    common stock outstanding.....  12,432,000 5,878,000   8,107,000   5,860,000
  b. shares attributable to
    redeemable convertible
    preferred stock..............         --  1,904,000   2,495,000   1,377,000
  c. shares attributable to
    common options and warrants..   1,848,000       --    3,359,000         --
                                   ========== =========  ========== ===========
                                   14,280,000 7,782,000  13,961,000   7,237,000
                                   ========== =========  ========== ===========
Pro forma diluted net income
 (loss) per share................  $     0.01 $   (0.03) $     0.07 $     (0.74)
                                   ========== =========  ========== ===========