EXHIBIT 21.1



Subsidiaries of the company



|         |  |                                                                                                                    
|-------- |  | -------------------------------------------------------------------------------------------------------------------
|1st Tier
|        |  | ManTech Command Control Systems Corporation, a Virginia corporation                                                
|        |  | ManTech MSM Security Services, Inc., a Maryland corporation                                                        
|        |  | ManTech CTX Corporation, a Virginia corporation                                                                    
|        |  | ManTech Integrated Data Systems Corporation, a Virginia corporation                                                
|        |  | ManTech Aegis Research Corporation, a Delaware corporation                                                         
|        |  | ManTech Solutions & Technologies Corporation, a Virginia corporation                                               
|        |  | ManTech Systems Engineering Corporation, a Virginia corporation                                                    
|        |  | ManTech Environmental Corporation, a Virginia corporation                                                          
|        |  | Science, Engineering and Analysis, Incorporated, a Virginia corporation                                            
|        |  | ManTech Support Technology, Inc., a Virginia corporation                                                           
|        |  | NSI Technology Services Corporation, a California corporation                                                      
|        |  | ManTech Advanced Systems International, Inc., a Virginia corporation                                               
|        |  | ManTech Telecommunications and Information Systems Corporation, a Delaware corporation                             
|        |  | ManTech Europe Systems Corporation, a Virginia corporation                                                         
|        |  | ManTech Australia Pty. Ltd., a corporation organized and existing under the laws of the Commonwealth of Australia  
|        |  | ManTech Australia International, Inc., a Virginia corporation                                                      
|        |  | ManTech U.K. Systems Corporation, a Virginia corporation                                                           
|        |  | ManTech Advanced Development Group, Inc., a California corporation                                                 
|        |  | ManTech Security Technologies Corporation                                                                          
|        
|2nd Tier
|        |  | Technology Management Corporation, a Virginia corporation                                                          
|        |  | ManTech Solutions Corporation, a Virginia corporation                                                              
|        |  | ManTech Systems Corporation, a New Jersey corporation                                                              
|        |  | ManTech Systems Solutions Corporation, a Virginia corporation                                                      
|        |  | MASI U.K. Limited, a corporation organized and existing under the laws of the United Kingdom                       
|        |  | Field Support Services Muhendislik Ltd. Sti., a corporation organized and existing under the laws of Turkey        
|        |  | Redesmundial, S.A., a corporation organized and existing under the laws of the Republic of Panama                  
|        |  | Praxa Limited, a corporation organized and existing under the laws of the New Zealand                              
|        |  | ManTech Europe, Ltd., a corporation organized and existing under the laws of the United Kingdom                    
|        |  | ManTech Test Systems, Inc., a Virginia corporation                                                                 
|        |  | ManTech Investigative Services, Inc., a Virginia corporation                                                       
|        |  | ManTech Environmental Research Services Corporation, a Virginia corporation                                        
|        
|3rd Tier
|        |  | ManTech Advanced Recognition Limited, a corporation organized and existing under the laws of the United Kingdom    
|        |  | ManTech Database Services Europe Limited, a corporation organized and existing under the laws of the United Kingdom