In the treatment of the nonunion of the long bone, it is very difficult to achieve union. We have attempted to treat 14 cases of nonunion in the long bones with onlay bone graft and cancellous chip bone graft from Jan. 1986 to Mar. 1990 at the department of Orthopaedic Surgery, Choong Ang Gil Hospital. l. 13 of 14 cases (92.9%) had complete bony union and the mean time of bone union is 6.2 months. 2. In Crenshaw's method, 7 of 8 cases had satisfactory bony union within 6.3 months average and in Phemister's method, all cases had complete bony union within 6.0 months average. 3. Therefore, onlay bone graft (Crenshaw or Phemister method) was proved to be one of valuable adjuvant methods in treatment of nonunion of the long bones.