Blunt diaphragm rupture in and of itself is seldom acutely fatal. But it can he associated with severe life threatening abdominal or thoracic injuries. Late presentation of diaphragm rupture, particulary in the strangulation phase, is associated with greatly increased mortality directly attrihutable to the diaphragm rupture. We reviewed 37 patients at Yongdong Severance hospital from Jan. 1992 to Dec. 1996 in an attempt to; 1) evaluate the dit'ferences hetween the outcome of the cases with early diagnosis and delayed iliagnosis; and 2) identify factors contributing to diagnostic delay. Fourteen of 37(37.8%) blunt diaphragm rupture were missed on initial evaluation. As for the cause of injury. Driver accident had significantly grcater proportion of delayed diagnosis(71.4%) than early diagnosis(47.8%). Right diaphragm rupture was more frequently found in delayed diagnosis(28.6%) than early diagnosis(8.7%), hut there was no tatistical significance. Coincidental intraahdominal injuries had significantly greater proportion of early diagnosis(65.2%) than delayed cliagnosis (7,2%)(p=0.005). In herniation into the thoracic cavity. Delayed diagnosis(7I.4%) was more common than early diagnosis(39.1%). Shock (p=0.005) and transfused pocked red cell(p=0.001) were significantly greater in early diagnosis than delayed diagnosis. Injury severity score and Glasgov, coma scale, duration of lCU. Hospital day and duration of ventilator showed no difference betwecn the two groups. In delayed diagnosis, only four of 14(28.6% ) were admitted to department of surgery or thoracic surgery. All patients with early diagnosis were admitted to the department of surgery or chest surgery. Five patients with early diagnosis died due to associated injuries. No patients died in case of delayed diagnosis. In conclusion. Blunt diaphragm rupture is difficult to diagnose and remains a. marker of severe combined injuries. In absence of indications for immediate operation I.e. associated intraabdominal injury, shock, and massive transfusion, patients with equivocal radiologic findings should be admitted to general or thoracic surgery and repeatedly examined to prevent delays in diagnosis.