PURPOSE: Monteggia fracture is a combination of ulnar fracture and radial head dislocation. Despite of low incidence, Monteggia fracture has a problem in the treatment. So satisfactory results could not be achieved easily. The purpose of this study was to analyze factors affecting functional results in Monteggia fracture. MATERIALS AND METHODS: From January 1990 to June 1998, we retrospectively reviewed 24 patients out of 40 patients who had been treated for Monteggia fracture. The functional assessment was performed with Broberg and Morrey system10). RESULTS: Excellent and good results were achieved in 16 cases(66.6%), whereas fair and poor results in 8 cases(33.4%). Satisfactory results were obtained in 66.6% overall. According to the Bado classification, functional results were not different significantly between types. According to the mechanisms of injury, unsatisfactory results were obtained in 8 of 17 patients with high energy injury. Monteggia fractures with ulnar fracture at the diaphyseal level showed satisfactory results significantly compared to others. In terms of the methods of internal fixation, the plate and screw fixation showed satisfactory results in 14 of 16 patients whereas tension band wiring or intramedullary nailing showed unsatisfactory results in 6 of 8 patients. CONCLUSION: In Monteggia fractures, factors affecting functional result may be the mechanism of injury, the level of ulnar fracture and the method of internal fixation.