Twelve Monteggia fractures were treated from 1996 to 2002 in our hospital. We evaluated their clinical results for this fracture. The subjects were all male. The average age of injury was 17.5 years. There were 8 children (under 15 years) and 4 adults (over 16 years). The mechanism of action of this fracture was 5 traffic accidents, 4 falls, and 3 others. Using the Bado classification, 6 were Type I , 3 Type II , and 3 Type III. There was no Type IV. There were 3 open fractures, 1 delayed union, and no nonunion. We attempted manual reduction in some children without anesthesia, but could not reduce completely. Consequently, we had to perform reduction again and immobilization later under anesthesia. The first operation was carried out 0.7 days (0 to 5 days) after injury. The most popular operation is osteosynthesis with kirschner wire. Many cases achieved excellent results, and 2 patients had poor. One had multiple trauma and internal medicine disease, and the other had flexor muscles hard injury.