As a result of experimental data and favorable clinical impressions, the pneumatic antishock garment (PASG) has gained widespread acceptance as a reasonable standard of care in emergency medical services (EMS) systems. It is currently legislated as required equipment for medical rescue vehicles in two-thirds of the United States. But despite a decade of widespread use, prospective, randomized, controlled trials that demonstrate the efficacy of the PASG have not been published. Furthermore, certain complications have been reported and concerns have been raised about the use of the PASG under certain circumstances, such as penetrating thoracic injury. In the fall of 1983, the City of Houston EMS system embarked on a long-term prospective evaluation of PASG use in hypotensive victims of injury in the urban prehospital setting. All victims of injury whose systolic blood pressure was 90 mm Hg or less when they initially presented to paramedics in the field were entered into the study. All patients received the identical treatment protocol, with the sole exception of PASG application and inflation to full pressure prior to intravenous catheterization on an alternate day basis. Prospectively collected demographic data have demonstrated that the two resulting groups of PASG and no-PASG patients are well matched in terms of age, sex, injury type, anatomic location of the injury, initial field trauma score, injury severity score and probabilities of survival, as well as the amounts of IV fluids infused in the prehospital setting and the response, scene, and transport times.(ABSTRACT TRUNCATED AT 250 WORDS)