Prehospital advanced trauma life support (ATLS) is controversial because the risks, benefits, and time required to accomplish it remain unknown. We studied 70 consecutive patients with penetrating cardiac injuries to determine the relationships among prehospital procedures, time consumed in the field, and ultimate patient outcome. Thirty-one patients sustained gunshot wounds, and 39 had stab wounds. The mean Revised Trauma Score was 2.8 +/- 0.5. Paramedics spent an average of 10.7 +/- 0.5 minutes at the scene. Seventy-one percent of the patients underwent endotracheal intubation; 93% had at least one IV line inserted; and 57% had two IV lines inserted. Twenty-one (30%) survived. There was no correlation between on-scene time and either the total number of procedures performed (r = .17, P = .17) or IV lines established (r = .06, P = .6). On-scene times did not differ regardless of whether endotracheal intubation or pneumatic antishock garment applications occurred. We conclude that well-trained urban paramedics can perform multiple life-support procedures with very short on-scene times and a high rate of patient survival and that prehospital trauma systems require a minimum obligatory on-scene time to locate patients and prepare them for transport.