Abstract Traumatic rupture of the diaphragm is an occult and often dangerous injury which is encountered with increasing frequency as a result of the growing number of automobile accidents. Although rarely lethal, it may threaten life by upsetting cardiorespiratory dynamics or it can cause chronic gastrointestinal symptoms for many years before presenting with obstruction or strangulation. The experience with thirty-two patients in three Rochester hospitals is reviewed. Anatomic studies suggesting reasons for the most common location of rupture are presented. Immediate repair is advocated when necessary for relief of cardiorespiratory symptoms in the seriously injured patient. Operation in others should be performed early, when feasible, to eliminate chronic symptoms and later serious complications. Because of the nature and frequency of associated intra-abdominal injuries, the abdominal or thoracoabdominal incision is recommended for repair of the left diaphragm in acutely injured patients. Thoracotomy is advised for repair of the unusual right diaphragmatic rupture, and thoracotomy is also preferred in the management of patients treated during the chronic phase of the disease.