PURPOSE: To evaluate the methods of treatment to obtain rigid fixation for nonunion of humerus shaft fractures developed after operative treatment. MATERIALS AND METHODS: From January 1993 to January 2000, twenty-one patients of nonunion of humerus shaft after primary internal fixation were reviewed and the results were analyzed. Three cases who have loss of follow-up were excluded. RESULTS: In twenty-one cases, nineteen had union but, two cases have failed. In the group of compression plate fixation and bone graft, bone union was completed at mean 4.4 months, in the group of IM nailing and bone graft at 4.9 months, in case of bone graft only with state of IM nailing at 5.5 months. Mean time until bone union was 4.6 months. CONCLUSION: Distraction should be avoided during IM nailing at primary internal fixation. Secondly, To obtain rigid fixation in nonunion of humerus shaft after primary internal fixation, use larger and more broad plate, dual plate or IM nail.