Aseptic nonunion of the ulna is a major complication of forearm fractures, accounting for 2% to 10% of all forearm fractures. Our study aims to evaluate the functional and radiological results of surgical treatment of diaphyseal aseptic nonunion of the ulna, with autologous bone grafting and internal plate fixation. A series of 20 patients were prospectively reviewed, the average age was 35 years with a mean of 36,60 years (range 20-63 years). Anderson's score was used to evaluate our results. Fifteen had very excellent results, four good and one poor. Consolidation of the no united ulnar fracture was attained in 6.2 months. Therefore, the functional prognosis of the upper limb imposes the need for adequate treatment. This management strategy has enabled us to have satisfactory results. However, the best treatment for nonunion remains the preventive treatment with optimal management and care of the forearm fractures.