Monteggia fracture-dislocation was described as a fracture of proximal third of the ulnar with a dislocation of radial head by G. Monteggia in 1814. Bado named Monteggia lesion as a fracture of ulnar at any level and a dislocation of radial head. The authors reviewed sixty-three patents of Monteggia fracture who were treated at department of orthopedic surgery, Yonsei university college of medicine from 1980. 1. to 1985. 12. We emphasis especially on cause of injury, classification, direction of radial head dislocation, level of ulnar fracture site, treatment and result. The results were as follows: 1. There were 22 children and 41 adults among 63 patients. 2. The male was affected more frequenty than female (49:14). The ratio between male and female was 3.5:l. 3. The most common cause of injury was falling down (54%) in children and car accident (51%) in adults. 4. According to Bado classification, type I was 68%, type II 11%, type III 18% and type IV 3%. 5. The partial posterior interosseous nerve injury was noticed in 12 cases and the superficial radial nerve injury was in 3 cases. The nerve injury was recovered spontaneously in all cases. Dislocation of radial head was as follows: Anterior dislocation was 38%, anterolateral 41%, lateral 8%, posterior 10% and posterolateral 3 % 7. Location of ulnar fracture site was as follows: Metaphysis was 22%, proximal 1/3 24%, junction of proximal 1/3 and middle 1/3 38%, middle 1/3 14% and distal 1/3 2%. 8. Closed reduction of radal head dislocation was done in 45 cases, open reduction in 10 cases and radial head excision in 6 cases. 9. Closed reduction of ulnar fracture was done in 26 cases and open reduction 35 cases. 10. We obtained 93% favorable results in children and 71% in adults. Not only the prognosis of ch ildren was better than adults but also the recovery time of children was shorter than adult's.