We have experienced 21 cases of traumatic diaphragm injury between October, 1989 and September, 1993. Of these patients, 17 cases were caused by blunt trauma and 4 by penetrating injury. Among 17 blunt traumas, 10 cases developed at left side, 6 at right and 1 at central subpericardial diaphragm, and among penetrating injuries, 3 cases developed at right side and 1 at left. Overall mortality rate was 21% and one due to blunt trauma was 29%. Initial hypotension was a predisposing factor to presume future death. When associated injuries involved 4 or more organs, mortality rate was high.