Introduction: Most of fractures of the shaft of the humeral shaft heal well when treated nonoperatively, nonunion is not a rare complication. The prevalence of nonunion as a complication of both nonoperative and operative treatment has been reported to be as high as 13%. Open reduction and plate fixation combined with autologous bone grafting can result in reliable healing of these humeral nonunions with excellent functional outcome. Material and Methods: Between 2009 and 2014, 30 nonunion cases of the humeral shaft were treated with open reduction and internal fixation by a plating. The series included 10 female patients and 20 male patients with an average age of 40years (range 20–60 years). The patients were followed up for an average of 18 months. The time from diagnosis of nonunion to our treatment of the nonunion averaged 9 months (range 6–24 months). Result: According to the Stewart and Hundley Criteria, the functional postoperative result was excellent or good in 22 (73%) cases and fair in eight (27%) cases. One year after surgery, all patients had an essentially normal range of motion of the ipsilateral elbow and shoulder. Conclusion: Surgical compression plating and autologous bone grafting of humeral diaphyseal nonunions resulted in 100% union rate and mostly excellent or good functional results without significant morbidity.