Twenty patients underwent surgical reconstruction for nonunion of fractures of the surgical neck of the humerus. Average time from injury to surgery was 10 months (range 4 to 14 months). The operation consisted of bone grafting combined with humeral head replacement in 10 cases and open reduction and internal fixation in 10 cases. Results, at an average follow-up of 51 months (range 24 to 124 months), were excellent in five (25%), satisfactory in six (30%), and unsatisfactory in nine (45%). Twelve nonunions resulted from fractures initially treated with close reduction; repair of these nonunions achieved by 67% excellent or satisfactory results. Eight nonunions resulted from fractures initially treated with internal fixation; repair of these nonunions achieved only 38% excellent or satisfactory results. Fifteen complications, 11 of which necessitated reoperation, occurred. Surgical reconstruction for nonunions of the surgical neck of the humerus usually results in significant improvement in pain but much more modest improvement in active motion and function. Surgery should be reserved for patients with significant symptoms and disability.