Twenty-eight patients were treated for humeral shaft nonunions. Host factors associated with humeral nonunion included a high rate of significant medical problems and significant local tissue trauma from the initiating injury. Comminuted fractures and fractures that were either long oblique or spiral in configuration were also heavily represented in this series. Midshaft was the most common anatomic location (n = 17). Previous surgery had been unsuccessful in 22 of the patients. All the humeral nonunions were treated by either standard AO compression plate technique with iliac crest bone grafting or, in patients with severely compromised bone from osteoporosis or multiple fixation attempts, a reconstruction using an intramedullary fibular graft and dynamic compression plate with screws, obtaining four cortices of fixation (quadricortical). This construction was also augmented with iliac crest bone graft. In this difficult subgroup of patients, our technique of intramedullary quadricortical fixation yielded an 89% union rate (17/19). Patients with humeral union were satisfied and had functional range of motion of the shoulder and elbow.