<PAGE>
 
                                                                    EXHIBIT 11.2
                         NEWBRIDGE NETWORKS CORPORATION

                       COMPUTATION OF EARNINGS PER SHARE

        (Accounting principles generally accepted in the United States)
         (Canadian dollars, amounts in thousands except per share data)
                                  (Unaudited)


<TABLE> 
<CAPTION> 
                                                        Fiscal quarters ended   Three fiscal quarters ended
                                                        ---------------------   --------------------------
                                                          Jan 31,     Feb 1,        Jan 31,       Feb 1,
                                                           1999        1998          1999          1998
                                                        ---------  -----------    ---------    ----------
<S>                                                    <C>        <C>            <C>          <C>
NET EARNINGS (LOSS) - U.S. GAAP                                                             
  Net earnings (loss), as reported, Cdn GAAP             $120,119   $(144,283)     $208,953     $(21,936)
                                                                                            
 Write off of purchased research and                                                        
   development in process                                      --     (52,762)           --      (52,762)
                                                                                            
 Amortization of purchased research and                                                     
  development in process, Cdn GAAP                             --      26,381            --       26,381
                                                         --------   ---------      --------     --------
                                                                                            
Net earnings (loss), U.S. GAAP                           $120,119   $(170,664)     $208,953     $(48,317)
                                                         ========   =========      ========     ========
                                                                                            
EARNINGS (LOSS) PER SHARE (U.S. GAAP - BASIC)                                               
                                                                                            
 Net earnings (loss)                                     $120,119   $(170,664)     $208,953     $(48,317)
                                                         ========   =========      ========     ========
                                                                                            
 Weighted average number of Common                                                          
   Shares outstanding during the period                   177,596     175,376       176,814      174,338
                                                         ========   =========      ========     ========
                                                                                            
 Earnings (loss) per share (U.S. GAAP)                   $   0.68   $   (0.97)     $   1.18     $  (0.28)
                                                         ========   =========      ========     ========
                                                                                            
EARNINGS (LOSS) PER SHARE (U.S. GAAP- DILUTED)                                              
                                                                                            
 Net earnings (loss)                                    $120,119   $(170,664)     $208,953     $(48,317)
                                                        ========   =========      ========     ========
                                                                                            
  Weighted average number of Common Shares                                                  
    outstanding during the period                        177,596     175,376       176,814      174,338
                                                                                            
 Net effect of dilutive stock options                                                       
   based on the treasury stock method                      4,434          --            --           --
                                                        --------   ---------      --------     --------
                                                                                            
 Weighted average number of Common                                                          
    Shares and equivalents outstanding                                                      
    during the period                                    182,030     175,376       176,814      174,338
                                                        ========   =========      ========     ========
                                                                                            
                                                                                            
 Earnings (loss) per share (U.S. GAAP)                  $   0.66   $   (0.97)     $   1.18     $  (0.28)
                                                        ========   =========      ========     ========
                                                                                            
EARNINGS (LOSS) PER SHARE EXPRESSED IN U.S. DOLLARS                                         
                                                                                            
  Daily average exchange rate of a Canadian                                                 
  dollar for U.S. dollars as reported by the                                                
    Federal Reserve Bank of New York                    $ 0.6515   $  0.7006      $ 0.6618     $ 0.7071
                                                                                            
 Earnings (loss) per share (U.S. GAAP)                                                      
   - Basic, in U.S. dollars                             $   0.44   $   (0.68)     $   0.78     $  (0.20)
                                                        ========   =========      ========     ========
                                                                                            
 Earnings (loss) per share (U.S. GAAP)                                                      
   - Diluted, in U.S. dollars                           $   0.43   $   (0.68)     $   0.78     $  (0.20)
                                                        ========   =========      ========     ========
</TABLE>
                                (Page 31 of 32)