We reviewed the recent experience with urgent thoracotomy performed in the operating room (OR) to compare the relative indications and injury pattern after blunt versus penetrating trauma. Among 2,316 patients admitted with acute trauma of the chest, excluding 319 undergoing thoracotomy at the emergency department, 83 required urgent OR thoracotomy; 27 patients (3 percent) sustained blunt trauma, 32 (4 percent) had stab wounds (SW) and 24 (7 percent) had gunshot wounds (GSW). The indications for operation after blunt trauma were shock (48 percent) and angiographically defined great vessel injuries (48 percent). For SW, thoracotomy was done for tamponade (50 percent), excessive chest tube output (28 percent) or shock (15 percent), and for GSW, thoracostomy output (50 percent), shock (25 percent) or tamponade (12.5 percent). Descending thoracic aorta (DTA) or other arch vessel tears were confirmed in 48 percent of patients with blunt trauma requiring thoracotomy; the remaining had pulmonary (31 percent) or cardiac wounds (7 percent). The most frequently encountered injuries in patients with SW were cardiac (46 percent) and pulmonary (37 percent), while the patients with GSW had predominantly pulmonary (72 percent) and cardiac (14 percent) injuries. The surgical management of blunt versus penetrating chest trauma differs with respect to the indications for urgent thoracotomy as well as the underlying injury pattern. The most common indication for urgent thoracotomy after penetrating injuries was excessive chest tube output (37.5 percent). Excluding torn DTA, only 14 of 822 patients (1.7 percent) admitted with blunt chest trauma required urgent thoracotomy and 13 of these patients (93 percent) presented in a state of refractory shock because of active thoracic hemorrhage. Thus, in contrast with penetrating wounds, urgent thoracotomy for blunt trauma is rarely justified on the basis of chest tube output alone.