The charts of 175 patients who underwent emergency thoracotomy (ET) in the emergency room (ER) between 1972 and 1978 were reviewed to determine the efficacy of this procedure. Seven cases of nontraumatic cardiac arrest were excluded from analysis. Although 150 patients were transported to the ER within 1 hour of injury, 60% either had no vital signs (91 cases) or were agonal (20 cases) on admission to the ER. The trauma was blunt in 60 cases and penetrating in 108. The major sites of injury were heart, major vessels, head, liver, and lung. Thirty-six patients died in the ER, 83 died in the operating room, and eight of the remaining 49 patients who survived operation died acutely in the immediate postoperative period. Of the patients who survived beyond 24 hours after injury 80% recovered and left the hospital: overall 19.6% survived. If patients with irreversible head injuries are eliminated, 24% survived. Correlation of admission status with outcome revealed the following survival rates: no vital signs (6.6%); agonal (20%); profound shock (34.1%); and mild shock with subsequent deterioration (56.3%). Survival rates were higher for patients with stab wounds (40%), pericardial tamponade (38%), and injury to the heart (30%), or lungs (57%). A cost-benefit analysis revealed that total benefits were 2.4 times greater than total costs. Performing early thoracotomy in the ER is a life-saving measure for a substantial number of trauma patients who present to the ERin extremis.