1 EXHIBIT 21 LIST OF SUBSIDIARIES NAME PLACE OF ORGANIZATION Subsidiaries of Rural/Metro Corporation (Delaware): Aid Ambulance at Vigo County, Inc. Indiana Ambulance Transport Systems, Inc. New York City Wide Ambulance Service, Inc. Ohio Donlock, Ltd. Pennsylvania Medical Emergency Devices and Services (MEDS), Inc. Arizona Metro Care Corp. Ohio 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 R/M Partners, Inc. Delaware RMFD of New Jersey, Inc. Delaware Rural/Metro Communications Services, Inc. Delaware Rural/Metro Corporation Arizona Rural/Metro International, Inc. Delaware Rural/Metro Mid-Atlantic, Inc. Delaware Rural/Metro of Colorado, Inc. Delaware SW General, Inc. Arizona South Georgia Emergency Medical Services, Inc. Georgia Southwest Ambulance of Casa Grande, Inc. Arizona Southwest General Services, Inc. Arizona The Aid Company, Inc. Indiana United Medical Services, Inc. Washington Subsidiaries of Rural/Metro Corporation (Arizona): Coronado Health Services, Inc. Arizona R/M Management Co., Inc. Arizona R/M of Mississippi, Inc. Delaware R/M Servicios de Salude e Incendios (Bolivia) S.A. (2%) Bolivia RMC Corporate Center, L.L.C. (1%) Arizona RMC Insurance Ltd. Barbados Rural/Metro Corporation of Florida Florida Rural/Metro Corporation of Tennessee Tennessee Rural/Metro Fire Dept., Inc. Arizona Rural/Metro Texas Holdings, Inc. Delaware Rural/Metro of Alabama, Inc. Delaware Rural/Metro of Arkansas, Inc. Delaware Rural/Metro of California, Inc. Delaware Rural/Metro of Georgia, Inc. Delaware Rural/Metro of Indiana, Inc. Delaware Rural/Metro of Kentucky, Inc. Delaware Rural/Metro of Nebraska, Inc. Delaware Rural/Metro of New York, Inc. Delaware Rural/Metro of Ohio, Inc. Delaware Rural/Metro of Oregon, Inc. Delaware 2 Rural/Metro of South Carolina, Inc. Delaware Rural/Metro of South Dakota, Inc. Delaware Rural/Metro Protection Services, Inc. Delaware W & W Leasing Company, Inc. Arizona 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 Subsidiaries of R/M of Texas G.P., Inc.: Rural/Metro of Texas, L.P. (99%) Delaware Subsidiaries of Rural/Metro Texas, Inc. Rural/Metro of Texas, L.P. (1%) Delaware Subsidiaries of Rural/Metro Corporation of Florida: Rural/Metro of North Florida, Inc. Florida Subsidiaries of Rural/Metro of New York, Inc.: Corning Ambulance Service Inc. New York Eastern Paramedics, Inc. Delaware LaSalle Ambulance, Inc. New York Rural/Metro of Rochester, Inc. New York Towns Ambulance Service, Inc. New York The Western New York Emergency Medical Services Training Institute Inc. (1) New York Subsidiaries of Rural/Metro of Rochester, Inc.: Beacon Transportation, Inc. New York National Ambulance & Oxygen Service, Inc. New York Subsidiaries of Rural/Metro of Nebraska, Inc.: Eastern Ambulance Service, Inc. Nebraska Subsidiaries of Eastern Ambulance Service, Inc.: Eastern Ambulance Service, Inc. - Lincoln (50% owned) Nebraska Subsidiaries of Rural/Metro of Ohio, Inc.: Gold Cross Ambulance Services, Inc. Delaware Physicians Ambulance Service, Inc. Delaware Rural/Metro of Central Ohio, Inc. Delaware Subsidiaries of Rural/Metro of Georgia, Inc.: Georgia E.M.S. Ventures, Inc. Delaware Medi-Cab of Georgia, Inc. 2 3 Subsidiaries of MO-RO-KO, Inc.: Southwest Ambulance of Tucson, Inc. Arizona Subsidiaries of Rural/Metro of South Carolina, Inc.: EMS Ventures of South Carolina, Inc. South Carolina Subsidiaries of Rural/Metro of Central Ohio, Inc.: American Limousine Service, Inc. Ohio Subsidiaries of Gold Cross Ambulance Services, Inc.: Gold Cross Ambulance Service of Pa., Inc. Ohio Subsidiaries of Rural/Metro Corporation of Tennessee: R/M of Tennessee G.P., Inc. Delaware R/M of Tennessee L.P., Inc. Delaware Subsidiaries of Rural/Metro of Indiana, Inc.: The Aid Ambulance Company, Inc. Delaware Subsidiaries of Rural/Metro of Alabama, Inc.: Medstar Emergency Medical Services, Inc. Delaware Rural/Metro of Central Alabama, Inc. Delaware RISC America Alabama Fire Safety Services, Inc. Delaware 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 Subsidiaries of Rural/Metro of Oregon, Inc.: Valley Fire Service, Inc. Delaware Subsidiaries of Rural/Metro of Kentucky, Inc.: Mercury Ambulance Service, Inc. Kentucky Subsidiaries of Rural/Metro of California, Inc.: Rural/Metro of San Diego, Inc. California Subsidiaries of Rural/Metro of San Diego, Inc.: 3 4 San Diego Medical Services Enterprise, LLC (50%) California Subsidiaries of R/M Management Co., Inc.: R/M Servicios de Salud e Incendios (Bolivia) S.A. (2%) Bolivia Subsidiaries of R/M Partners, Inc.: Rural/Metro Mid-Atlantic II, Inc. (50%) Delaware We Care Bus Transportation, Inc. (33%) New York We Care Transportation, Inc. (33%) New York Subsidiaries of Rural/Metro Mid-Atlantic II, Inc.: Mobile Medical Transportation, Inc. Maryland Subsidiaries of Mobile Medical Transportation, Inc.: Choice American Ambulance Service, Inc. Virginia Subsidiaries of Rural/Metro of Colorado, Inc.: Rural/Metro of Central Colorado, Inc. Delaware Subsidiaries of Ambulance Transport Systems, Inc.: Keefe & Keefe, Inc. New York Keefe & Keefe Ambulette, Ltd. New York Subsidiaries of Keefe & Keefe, Inc.: Multi-Cab, Inc. New Jersey Multi-Care International, Inc. New Jersey Subsidiaries of United Medical Services, Inc.: Arrow Ambulance, Inc. Idaho Subsidiaries of R/M of Mississippi, Inc.: Rural/Metro of Mississippi, Inc. Delaware Subsidiaries of RMC Insurance Ltd.: RMC Corporate Center, L.L.C. (99%) Arizona Subsidiaries of North Mississippi Ambulance Service, Inc.: Rural/Metro Mid-South, L.P. (1%) Delaware Subsidiaries of R/M of Tennessee G.P., Inc.: Rural/Metro of Tennessee, L.P. (99%) Delaware Rural/Metro of Mid-South, L.P. (99%) Delaware 4 5 Subsidiaries of R/M of Tennessee L.P., Inc.: Rural/Metro of Tennessee, L.P. (1%) Delaware Subsidiaries of The Aid Ambulance Company, Inc.: Rural/Metro of Indiana, L.P. (99%) Delaware Rural/Metro of Indiana II, L.P. (99%) Delaware Subsidiaries of The Aid Company, Inc.: Rural/Metro of Indiana, L.P. (1%) Delaware Subsidiaries of Aid Ambulance at Vigo County, Inc.: Rural/Metro of Indiana II, L.P. (1%) Delaware Subsidiaries of Rural/Metro International, Inc.: Rural/Metro Argentina, L.L.C. Arizona Rural/Metro of Argentina, Inc. Delaware Rural/Metro Canadian Holdings, Inc. Delaware Rural/Metro of Brasil, Inc. Delaware Rural/Metro Brasil, L.L.C. Arizona Rural/Metro of Netherlands Holdings, B.U. Netherlands Rural/Metro of Argentina, S.A. (1%) Argentina Subsidiaries of Rural/Metro Argentina, L.L.C.: Rural/Metro Inversora, S.R.L. Argentina Subsidiaries of Rural/Metro Canadian Holdings, Inc.: Rural/Metro of Canada Company Nova Scotia Subsidiaries of Rural/Metro of Canada Company: Rural Metro of Ontario Company Nova Scotia Subsidiaries of Rural/Metro of Ontario Company: 3012525 Nova Scotia Company Nova Scotia Lindsay and District Ambulance Service Company Nova Scotia Lakeshore Emergency Service Company Nova Scotia Owen Sound Emergency Services Company Nova Scotia Noel Ambulance Service Company Nova Scotia Port Colborne & District Ambulance Service Company Nova Scotia Subsidiaries of Rural/Metro Netherlands Holdings, B.V.: Rural/Metro of Argentina, S.A. (99%) Argentina Subsidiaries of Rural/Metro of Argentina, S.A.: 5 (1) Merged with and into LaSalle Ambulance, Inc., effective August 10, 1998. 6 Marlon S.A. Argentina Peimu S.A. Argentina Recor S.A. Argentina Semercor S.A. Argentina Subsidiaries of Rural/Metro Brazil, L.L.C.: Line of Duty, Ltda (99%) Brazil Subsidiaries of Rural/Metro of Brazil, Inc.: Line of Duty, Ltda (1%) Brazil 6