EXHIBIT 21



SUBSIDIARY LIST

AS OF SEPTEMBER
28, 2004



|                                                    |  |              |  |                                                                                                      
|--------------------------------------------------- |  | ------------ |  | -----------------------------------------------------------------------------------------------------
|NAME                                                |  | STATE        |  | NAMES UNDERWHICH ENTITY DOES BUSINESS                                                                
|Overall Parent Company:                             |  |              |  |                                                                                                      
|                                                    |  |             
|Rural/Metro Corporation                             |  | Delaware     |  |                                                                                                      
|                                                    |  |             
|Subsidiaries of Rural/Metro Corporation (Delaware): |  |              |  |                                                                                                      
|                                                    |  |             
|Aid Ambulance at Vigo County, Inc.                  |  | Indiana      |  |                                                                                                      
|Ambulance Transport Systems, Inc.                   |  | New Jersey   |  |                                                                                                      
|Donlock, Ltd.                                       |  | Pennsylvania |  | Rural/Metro Medical Services, Ltd.; Rural/Metro Ambulance, Ltd.                                      
|Medical Emergency Devices and Services (MEDS), Inc. |  | Arizona      |  | MEDS & Logo                                                                                          
|Metro Care Corp.                                    |  | Ohio         |  | Rural/Metro Ambulance                                                                                
|MO-RO-KO, Inc.                                      |  | Arizona      |  |                                                                                                      
|Multi-Care Medical Car Service, Inc.                |  | New Jersey   |  |                                                                                                      
|Multi-Health Corp.                                  |  | Florida      |  |                                                                                                      
|Myers Ambulance Service, Inc.                       |  | Indiana      |  |                                                                                                      
|North Miss. Ambulance Service, Inc.                 |  | Mississippi  |  |                                                                                                      
|Professional Medical Services, Inc.                 |  | Arkansas     |  |                                                                                                      
|RMFD of New Jersey, Inc.                            |  | Delaware     |  |                                                                                                      
|R/M Partners, Inc.                                  |  | Delaware     |  |                                                                                                      
|Rural/Metro Communications Services, Inc.           |  | Delaware     |  |                                                                                                      
|Rural/Metro Corporation                             |  | Arizona      |  | Rural/Metro Ambulance Service, AMT, Arizona Medical Transport, Tri-City Med                          
|Rural/Metro Logistics, Inc.                         |  | Delaware     |  |                                                                                                      
|Rural/Metro Mid-Atlantic, Inc.                      |  | Delaware     |  |                                                                                                      
|Rural/Metro of Colorado, Inc.                       |  | Delaware     |  |                                                                                                      
|Rural/Metro of Greater Seattle, Inc.                |  | Washington   |  | Rural/Metro Ambulance                                                                                
|Rural/Metro of Southern Ohio, Inc.                  |  | Ohio         |  | Rural/Metro Ambulance                                                                                
|SW General, Inc.                                    |  | Arizona      |  | Southwest Ambulance; Southwest Transportation Services; Southwest Medical Services; KIDZULANCE       
|                                                    |  |             
|South Georgia Emergency Medical Services, Inc.      |  | Georgia      |  |                                                                                                      
|Southwest Ambulance of Casa Grande, Inc.            |  | Arizona      |  | Southwest Ambulance and Rescue of Arizona; SWARA                                                     
|                                                    |  |             
|Southwest Ambulance of New Mexico, Inc.             |  | New Mexico   |  | Southwest Ambulance of Doña Ana County; Southwest Ambulance of Las Cruses; Southwest General Services
|                                                    |  |             
|Southwest General Services, Inc.                    |  | Arizona      |  | CareTrans; CareTrans Medicoach Services; SW General Services                                         
|                                                    |  |             
|The Aid Company, Inc.                               |  | Indiana      |  |                                                                                                      
|                                                    |  |             
|Subsidiaries of Rural/Metro Corporation (Arizona):  |  |              |  |                                                                                                      
|                                                    |  |             
|R/M Management Co., Inc.                            |  | Arizona      |  |                                                                                                      





---

|                                                          |  |                |  |                                                                                     
|--------------------------------------------------------- |  | -------------- |  | ------------------------------------------------------------------------------------
|Subsidiaries of Rural/Metro of Oregon, Inc.:              |  |                |  |                                                                                     
|                                                          |  |               
|Valley Fire Service, Inc.                                 |  | Delaware       |  | Rural/Metro Fire Department; Valley Fire Service Fire Service Research Co. of Oregon
|                                                          |  |               
|Subsidiaries of Rural/Metro of South Carolina, Inc.:      |  |                |  |                                                                                     
|                                                          |  |               
|EMS Ventures of South Carolina, Inc.                      |  | South Carolina |  |                                                                                     
|                                                          |  |               
|Subsidiaries of Rural/Metro of South Dakota, Inc.:        |  |                |  |                                                                                     
|                                                          |  |               
|Medical Transportation Services, Inc.                     |  | South Dakota   |  |                                                                                     
|                                                          |  |               
|Subsidiaries of Medical Transportation Services, Inc.:    |  |                |  |                                                                                     
|                                                          |  |               
|Sioux Falls Ambulance, Inc.                               |  | South Dakota   |  | Rural/Metro Ambulance                                                               
|                                                          |  |               
|Subsidiaries of Rural/Metro Texas Holdings, Inc.:         |  |                |  |                                                                                     
|                                                          |  |               
|R/M of Texas G.P., Inc.                                   |  | Delaware       |  |                                                                                     
|Rural/Metro of Arlington, Inc.                            |  | Delaware       |  |                                                                                     
|Rural/Metro of Texas, Inc.                                |  | Delaware       |  | Rural/Metro Ambulance                                                               
|                                                          |  |               
|Subsidiaries of R/M of Texas G.P., Inc.:                  |  |                |  |                                                                                     
|                                                          |  |               
|Rural/Metro of North Texas, L.P. (1%).                    |  | Delaware       |  | Rural/Metro Ambulance                                                               
|Rural/Metro of Texas, L.P. (1%)                           |  | Delaware       |  | Rural/Metro Ambulance, L.P.                                                         
|                                                          |  |               
|Subsidiaries of Rural/Metro of Texas, Inc.:               |  |                |  |                                                                                     
|                                                          |  |               
|Rural/Metro of North Texas, L.P. (99%).                   |  | Delaware       |  | Rural/Metro Ambulance                                                               
|Rural/Metro of Texas, L.P. (99%)                          |  | Delaware       |  | Rural/Metro Ambulance                                                               
|                                                          |  |               
|Subsidiaries of Southwest Ambulance of Casa Grande, Inc.: |  |                |  |                                                                                     
|                                                          |  |               
|Southwest Ambulance and Rescue of Arizona, Inc.           |  | Arizona        |  | Southwest Ambulance and Rescue of Arizona; SWARA                                    
|                                                          |  |               
|Subsidiaries of Southwest General Services, Inc.:         |  |                |  |                                                                                     
|                                                          |  |               
|Southwest General Services of Dallas, LLC (19.9%)         |  | Delaware       |  |                                                                                     
|                                                          |  |               
|Subsidiaries of The Aid Company, Inc.:                    |  |                |  |                                                                                     
|                                                          |  |               
|Rural/Metro of Indiana, L.P. (99%)                        |  | Delaware       |  |                                                                                     



LIMITED
PARTNERSHIPS



|                                |  |          |  |                                       
|------------------------------- |  | -------- |  | --------------------------------------
|NAME                            |  | STATE    |  | NAMES UNDER WHICH ENTITY DOES BUSINESS
|Rural/Metro Mid-South, L.P.     |  | Delaware |  |                                       
|Rural/Metro of Tennessee, L.P.  |  | Delaware |  | Rural/Metro Ambulance                 
|Rural/Metro of Indiana, L.P.    |  | Delaware |  |                                       
|Rural/Metro of Indiana II, L.P. |  | Delaware |  |                                       



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