In every serious thoracic or abdominal injury, or both, a hernia of the diaphragm should be suspected and always sought clinically and roentgenologically. If a hernia is present, compatible with the condition of the patient, it should be operated upon immediately. The choice of surgical access depends upon the associated lesions. We prefer thoracotomy as the surgical approach if important submesocolic lesions are not present. In instances of a late diagnosis, the approach should always be through the chest. The late results, in patients diagnosed and operated upon early, are good and are comparable with those obtained in operations of the thorax for nonneoplastic conditions. The surgical approach of choice for the treatment of such hernias is a thoracotomy both in the early as well as in the late stages, provided that no important submesocolic lesions are present.