EXHIBIT 21.1

Subsidiaries of the Company



|         |  |                                                                    
|-------- |  | -------------------------------------------------------------------
|1st Tier |  |                                                                    
|        |  | ManTech Advanced Development Group (CA)                            
|        |  | ManTech Advanced Systems International, Inc. (VA)                  
|        |  | ManTech Australia International Corporation (VA)                   
|        |  | ManTech Command Control Systems Corporation (VA)                   
|        |  | ManTech Cyber Solutions International, Inc. (DE)                   
|        |  | ManTech Europe Systems Corporation (VA)                            
|        |  | ManTech Gray Hawk Systems, Inc.                                    
|        |  | ManTech Global Services Corporation (VA)                           
|        |  | ManTech GRS Solutions, Inc. (MD)                                   
|        |  | ManTech Information Systems & Technology Corporation (VA)          
|        |  | ManTech MBI, Inc. (VA)                                             
|        |  | ManTech Mission Operations Corporation (DE)                        
|        |  | ManTech Security & Mission Assurance Corporation (DE)              
|        |  | ManTech Security Technologies Corporation (VA)                     
|        |  | ManTech Sensor Technologies Corporation (NJ)                       
|        |  | ManTech Solutions & Technologies Corporation (VA)                  
|        |  | ManTech SRS Technologies, Inc. (CA)                                
|        |  | ManTech Support Technology, Inc. (VA)                              
|        |  | ManTech Systems Engineering Corporation (VA)                       
|        |  | ManTech Telecommunications and Information Systems Corporation (DE)
|        |  | ManTech U.K. Systems Corporation (VA)                              
|        |  | NeXolve Corporation (VA)                                           
|        |  | NSI Technology Services Corporation (CA)                           
|         | 
|2nd Tier |  |                                                                    
|        |  | DB Data Systems, LLC (VA)                                          
|        |  | DDK Technology Group, Inc. (MD)                                    
|        |  | EWA-JV, LLC (VA)                                                   
|        |  | Field Support Services, Ltd. (Turkey)                              
|        |  | Gray Hawk Technology Solutions, L.L.C. (VA)                        
|        |  | Hawkeye Systems, LLC (VA)                                          
|        |  | INTEROP II Joint Venture (VA)                                      
|        |  | ManTech Australia Pty. Limited (Australia)                         
|        |  | ManTech Electronics Interoperability Services, Inc. (DE)           
|        |  | ManTech Environmental Research Services Corporation (VA)           
|        |  | ManTech ETG, LLC (DE)                                              
|        |  | ManTech Test Systems, Inc. (VA)                                    
|        |  | Symmetron Holding Corporation (VA)                                 
|        |  | Symmetron, LLC (VA)