Exhibit 21

AMERICAN POWER CONVERSION CORPORATION  Subsidiaries as of December 31, 2004

|Subsidiary                                          |                                                                            | Place of
Incorporation                     
|--------------------------------------------------- | -------------------------------------------------------------------------- | -------------------------------------------
|APC America, Inc.                                   |                                                                            | Delaware                                   
|APC Sales & Service Corp.                           |                                                                            | Delaware                                   
|American Power Conversion Holdings Inc.             |                                                                            | Delaware                                   
|Systems Enhancement Corporation                     |                                                                            | Missouri                                   
|A.B.L. Electronics Corporation                      |                                                                            | Delaware                                   
|APC DC Network Solutions Inc.                       |                                                                            | Ohio                                       
|American Power Conversion Europe S.A.R.L.           |                                                                            | France                                     
|American Power Conversion Corporation (A.P.C.) B.V. |                                                                            | The Netherlands                            
|                                                    | APC Distribution Limited                                                   |                                            
|                                                    | APC (EMEA) Limited                                                         |                                            
|                                                    | APC Holdings B.V.                                                          |                                            
|                                                    |                                                                            | APC Deutschland GmbH                       
|                                                    |                                                                            | American Power Conversion UK Ltd.          
|                                                    |                                                                            | American Power Conversion Sweden AB        
|                                                    |                                                                            | APC Benelux B.V.                           
|                                                    |                                                                            | APC Australia Pty Limited                  
|                                                    |                                                                            | American Power Conversion Portugal, Ltda.  
|                                                    |                                                                            | American Power Conversion Spain S.L.       
|                                                    |                                                                            | American Power Conversion Italia S.R.L.    
|                                                    |                                                                            | American Power Conversion France SARL      
|                                                    |                                                                            | APC Korea Corporation                      
|                                                    |                                                                            | American Power Conversion Hong Kong Limited
|                                                    |                                                                            | American Power Conversion Poland Sp. z.o.o.
|                                                    | American Power Conversion (Phils.), Inc.                                   |                                            
|                                                    | American Power Conversion Land Holdings Inc. (40%; 60% Filipino nationals) |                                            
|                                                    | APC (Suzhou) Uninterrupted Power Supply Co., Ltd.                          |                                            
|                                                    | American Power Conversion Singapore Pte Ltd.                               |                                            
|                                                    | APC International Trade (Shanghai) Co. Ltd.                                |                                            
|                                                    | APC Europe B.V.                                                            |                                            
|                                                    | APC (Xiamen) Power Infrastructure Co. Ltd.                                 |                                            
|American Power Conversion Denmark ApS               |                                                                            | Denmark                                    
|                                                    | Gutor Electronic GmbH                                                      |                                            
|                                                    | American Power Conversion Dublin Limited                                   |                                            
|                                                    | Silcon (Qingdao) Power Electronics Co. Ltd.                                |                                            
|                                                    | Gutor Electronic Asia Pacific Sdn Bhd                                      |                                            
|American Power Conversion Mexico, S.A. de C.V.      |                                                                            | Mexico                                     
|American Power Conversion Uruguay S.A.              |                                                                            | Uruguay                                    
|APC Japan, Inc.                                     |                                                                            | Japan                                      
|American Power Conversion (India) Private Limited   |                                                                            | India                                      
|American Power Conversion Brasil Ltda.              |                                                                            | Brazil                                     
|American Power Conversion Holdings (UK) Limited     |                                                                            | United Kingdom                             
|                                                    | APC DC Network Solutions UK Limited                                        |                                            

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