This nineteen-year retrospective review was designed to evaluate diaphragmatic hernias due to blunt thoracoabdominal trauma in a series of 50 patients. Motor-vehicle accidents were the most frequent cause. The diagnosis was made immediately after injury in 34 patients (acute hernias), but delayed from two months to 30 years in 16 (chronic hernias). Two patients, with multiple associated injuries, died soon after admission and diagnosis was made at necropsy. The nature of injury, the physical findings and the plain chest roentgenograms suggested a traumatic diaphragmatic hernia in most of the remaining acutely injured patients. All patients with chronic hernias had suggestive or suspicious abnormalities on chest roentgenograms; however, appropriate upper gastrointestinal tract and barium enema studies were of utmost importance for the correct diagnosis. Reduction of herniated viscera and repair of diaphragmatic defect were generally accomplished through a laparotomy in acute hernias, whereas thoracotomy was the preferred approach in delayed instances. There were four postoperative deaths, three with severe multiple associated injuries and one with respiratory failure.