Trauma to the thorax represents a significant portion of injuries seen in an inner-city emergency room. Although most of these patients may be successfully managed without thoracotomy, a certain percentage require operative intervention either immediately or within several hours. The records of more than 380 patients with major chest trauma seen in recent years have been reviewed. Three hundred twenty-one of these patients (84%) required only good supportive measures such as correction of hypovolemia, temporary ventilatory support, tube thoracostomy, and careful observation. Forty-four additional patients (12%) required immediate operation following preliminary resuscitative treatment. Indications included hemorrhage, cardiac tamponade, injury to a great vessel, and rupture of the diaphragm. There were 10 deaths in this group. In 15 other individuals (4%) delayed operation was undertaken following careful reappraisal of initial injuries by continued examination, monitoring of vital signs, and appropriate roentgenographic and laboratory studies. Indications for delayed operation included continued or recurrent bleeding, widening of the mediastinum, hemoptysis, and recurrent hemothorax. There was only 1 death in this group. Thus, although it may be clear which patients require immediate operation, only careful and continuous monitoring can identify those who initially appear to be in stable condition but eventually will require exploration.