Four hundred and twenty-seven patients with severe blunt chest trauma were treated resulting in (1) flail chest, (2) pulmonary contusions, (3) pneumothorax, (4) hemothorax, or (5) multiple rib fracture. The need for endotracheal intubation and mechanical ventilation was determined selectively by standard clinical criteria. Avoidance of fluid overload and vigorous pulmonary toilet was attempted in all patients. Three hundred and twenty-eight patients were treated by nonintubation; 318 patients (96.6%) had a successful outcome, while ten required intubation. Only one patient died. The 99 patients who required intubation and mechanical ventilation had a high mortality because of associated shock and head injury; however, the total mortality for the entire group of patients was 6.5%, with only 1.4% mortality caused by pulmonary injury. The incidence of pneumonia was high (51%), but there was only a 4% incidence of tracheostomy complications. Flail chest and pulmonary contusion without flail chest occurred in 95 and 135 patients, respectively. Half of the flail chest patients were intubated, but 69.5% were intubated less than three days. Twenty per cent of the patients with pulmonary contusion required mechanical ventilation, usually for less than three days. This study demonstrates that patients with severe blunt chest trauma can be managed safely by selective intubation and mechanical, ventilation and that the incidence of complications associated with controlled mechanical ventilation can be greatly reduced.