This study aimed at assessing the effectiveness of open reduction and plate fixation combined with autogenous bone grafting in the treatment of non-united fractures of the humeral shaft. Forty six patients (27 men, 19 women; mean age, 35.6 years; range, 23-53 years) were operated on for non-union of a diaphyseal fracture of the humerus. Sixteen patients had surgical treatments and 30 patients had non-surgical treatments prior to operation. They were operated on average 7.8 months (6-17) following their initial treatment. None of the nonunions were infected. Radial nerve deficit was present in no patient. Treatment included open reduction and plate fixation combined with autogenous bone grafting. The mean follow-up period was 26 months (range: 13-41). No patient was lost to follow-up. The operative time averaged 91 minutes (range: 68-123). Union was achieved in all patients in a mean of 6.1 months (range: 5-13). There were nine postoperative complications (superficial infection in 5 and radial nerve palsy in 4). The infections resolved after local treatment. The radial nerve palsies recovered spontaneously. On clinical evaluation, shoulder range of motion was excellent in 41 patients (89.1%), and moderate in five patients (10.9%). Elbow range of motion was excellent in 30 patients (65.2%), moderate in 14 patients (30.4%) and poor in 2 patients (4.4%). Functional results were excellent in 24 patients (522%), good in 14 patients (30.4%), fair in 6 patients and poor in 2 patients (04.4%). In this study, plate fixation combined with autogenous bone grafting appeared as a safe and effective option in non-infected non-union of the humeral shaft.