EXHIBIT 21.1 MRO SOFTWARE, INC. List of Subsidiaries -------------------- Jurisdiction of Name of Subsidiary Incorporation Ownership - ------------------ ------------- --------- MRO International Software, Inc. Delaware (1) MRO Security Corporation Massachusetts (1) MRO International Holdings, Inc. Delaware (2) PSDI Export, Inc. Barbados (1) MRO Software, UK Limited United Kingdom (2) MRO Software (Canada) Limited Canada (2) MRO Software S.A.R.L. France (2) MRO Software Australia Pty. Limited Australia (2) MRO Software GmbH Germany (2) PSDI Europe Ltd. United Kingdom (2) PSDI Espana S.A. Spain (2) MRO Software NV Netherlands (2) MRO Software AB Sweden (2) MRO Software Japan K.K. Japan (2) MRO Software (Thailand) Limited Thailand (2) MRO Software India Private Limited India (2) MRO Software do Brasil Ltda. Brazil (3) MRO Software Hong Kong Ltd. Hong Kong (2) MRO Software Mexico S.A. de C.V. Mexico (3) MRO Software (Shanghai) Co. Ltd China (1) MRO Software Italia s.r.l. Italy (1 & 2) MRO.com, Inc. Delaware (1) MRO.com, Limited United Kingdom (4) MRO.com, Limited Canada (4) MRO.com Pty Limited Australia (4) MRO.com (Asia) Limited Hong Kong (4) INTERMAT, Inc. Delaware (1) (1) All of the outstanding capital stock is owned by MRO Software, Inc. (2) All of the outstanding capital stock (other than certain qualifying shares required in the jurisdiction of organization and representing from 0% to 2% of the outstanding capital stock), is owned by MRO International Software, Inc. (3) 4,950 shares are owned by MRO International Software, Inc. and 50 shares are owned by MRO International Holdings, Inc. (4) All outstanding capital stock is owned by MRO.com, Inc. - -------------------------------------------------------------------------------- Page 66