Most humeral shaft fractures can be managed nonoperatively. Recently improved results have been reported after internal fixation of the humeral shaft fractures, followed by early elbow and shoulder motion. Authors carried out True/Flex intramedullary nail in 14 patients and interlocking intramedullary nail in 12 patients and plate & screw fixation in 18 patients who sustained humerus shaft fracture between February 1992 and August 1996. We compared the operative results of intramedullary nailing and plate and screw fixation in humeral shaft fractures which was follow-up from 12 months to 21 months. The results were as follows ; 1) The mean union time was at 16.5 weeks in True/Flex group, at 16 weeks in interlocking nail group, and at 15.7 weeks in plate fixation group. 2) The complications such as angulation(3 cases), rotation(1 case), limitation of shoulder motion(2 cases), and delayed union(1 case) were observed in True/Flex group. Angulation(1 case), rotation(1 case), limitation of shoulder motion(3 cases), and nonunion (1 case) in interlocking nail group. Angulation (1 case), limitation of elbow motion(2 cases), nonunion(1 case), soft tissue infection(2 cases), and iatrogenic radial nerve palsy (2 cases) were developed in plate fixation group.