OBJECTIVE To investigate the clinical results of locking compression plate combined with autologous iliac bone graft in the treatment of aseptic ulnar nonunion. METHODS From March 2009 to July 2017, 22 patients with aseptic ulnar diaphyseal nonunion with complete follow-up data were treated with surgery, including 12 males and 10 females, aged from 16 to 58 (39.7±9.9) years old and ranging in course of disease from 10 to 192 (39.4±55.7) months. There were 15 atrophic nonunions, 5 hypertrophic nonunions and 2 synovial pseudo-articular nonunions. After debridement of the nonunion, locking compression plate was used to fix the nonunion and autogenous iliac bone graft was given. Bone healing rate, surgical complications and clinical results were evaluated. RESULTS All the patients were followed up, and the duration ranged from 13 to 42 months, with a mean of (22.5±8.2) months, and 1 patient did not heal. Visual analogue pain scores ranged from 0 to 3 (0.9±0.9). Pronation of forearm was 47 to 86 (69.0±14.7) degrees, supination was 35 to 85 (63.0±9.4) degrees, wrist flexion was 20 to 80 (51.0±10.2) degrees, wrist flexion was 32 to 88 (71.0±11.7) degrees, elbow flexion contracture was 0 to 25 (9.0±5.6) degrees, further flexion was 105 to 150 (134.0±13.9) degrees, and grip strength was 87% on the opposite side. According to the Anderson scoring system, 8 cases were excellent, 11 were satisfied, 2 were not satisfied, and 1 was failed. CONCLUSIONS LCP combined with autologous iliac bone graft can effectively treat aseptic ulna diaphyseal nonunion.