Exhibit 21
                                                                      ----------

                                 Subsidiaries
                                 ------------

                                 Address of                      Jurisdiction of
    Name                         Principal Office                Incorporation
    ----                         ----------------                ---------------
                                                                
1.  Persist, S.A.                Avda. Sofia 45-53              
                                 Local Comercial Torre 7        
                                 08870 - Sitges (Barcelona)     
                                 Spain                           Spain
                                                                
2.  Peritus Software Services    2 Federal Street                Massachusetts
    Securities Corporation       Billerica, MA 01821            
                                                                
3.  Peritus Software Services    Gopalakrishna Complex           India
    (India) Private Limited      V Floor, 45/3, Residency Road   
                                 Bangalore, India               

4.  Millennium Dynamics, Inc.    2 Federal Street                Delaware
    (formerly Twoquay, Inc.)     Billerica, MA 01821