Fracture of the upper third of te ulna associated with dislocation of the head of the radius was first described by Monteggia in 1814. The most important factors in achieving good results in adults with Monteggia lesions are early accurate diagnosis, rigid internal fixation of the fractured ulna, and complete reduction of the dislocated radial head. The authors reviewed 17 patients of Monteggia fracture in adult who were treated at department of orthopedic surgery, Cho-Sun University Hospital from 1981. 1 to 1989. 12. The results obtained were as follows:1. Male is about 2 times more than female. 2. The causes of injuries were traffic accident 10, fall down 5, belt injury 1, and direct blowing l. 3. According to Bado classification, type I is most common type. and direction of radial head dislocation were as follow; anterior 5, anterolateral 8, lateral 2, posterolateral 2. 4. Location of ulna fracture site were upper one third 5, junction of upper and middle 1/3 5, middle 1/3 4, distal 1/3 1 and segmental 2. 5. Treatment of dislocated radial head were closed reduction in 7, open reduction in 2, and exision in 8. 6. Fractures of ulna were all treated with open reduction internal fixation with plate in 8, Rush pin in 5, and wiring in 4 cases. 7. Palsies of posterior interosseous nerve were observed in 2 patients and recovered completely later. 8. With the criteria of Bruce et al (1974), the results were excellent 6, good 4, fair 4, and poor 3. By the experience of the authors, it is the most important for the result of the treatment according to the degree of dislocated radial head and fracture of ulna at initial trauma. Most of all, it is necessary that the early diagnosis and reduction of dislocated radial head when doctor exams patient first time. At the same time, it is assumed that the rigid fixation of fractured ulna shows good results.