Within a 12-year period ending in March 1984, 1109 patients with penetrating thoracic injuries were treated at King-Drew Medical Center located in south central Los Angeles. The average age of the patients was 28.1 years. There were 607 stab wounds and 502 gunshot wounds. Antibiotic prophylaxis was prescribed only for the 428 patients who had laparotomy, thoracotomy, and pulmonary contusion with hemoptysis. Of the 1109 patients, 105 had cardiac injuries. All patients with cardiac trauma underwent thoracotomy, and the mortality rate was 18.1%. Specifically, the mortality rate of gunshot wound of the heart 24.5% and that of stab wound of the heart, 11.5%. In contrast, of the 1004 patients without cardiac injuries, only 115 required thoracotomy and the mortality rate in this group was 0.8% (8/1004). The mortality rate was 69.6% in patients who had a thoracotomy in the emergency room but only 2.8% in patients who had a thoracotomy in the operating room within the first 24 hours after admission. In the 242 patients who had associated abdominal injuries, the mortality rate was 2.1% (5/242), as compared with 2.5% (22/867) for those who had isolated chest injuries. In the entire group, the incidence of complications was 5.1%, of which 1.8% were infectious complications. The presence of associated abdominal injuries did not influence the outcome. The mortality rate in noncardiac thoracic injuries is very low compared with that of cardiac injury. Because of the complexity of the injury, gunshot wound of the heart has the highest mortality rate.