From Oct. 1974 to Jun. 1979, 47 diaphyseal fractures of the forearm bones in 36 patients were treated with compression plates. Among them 36 diaphyseal fractures in 28 patients (23 with acute fractures. and 5 with non-union) followed for average 8.3 months from three months to thirty seven months were studied. 19 fractures of the radius and 17 fractures of the ulna were treated with compression plates. Fifteen fractures which were delayed for operation for more than 3 weeks or had severe comminution, had primary iliac bone grafts. The fracture unlon of the radius and ulna was obtained in all cases and average healing time for the radius was 11.9 weeks and for the ulna was 12.3 weeks. The final functional results were excellent, 16 and satisfactory,7. The over all rates of excellent and satisfactory results were 82.2 percent. Therefore compression plate is one of the excellent methods to treat diaphyseal fractures and non-union of the forearm bone.