The cubitus varus is one of the most common complications of supracondylar fracture of humerus. The authors treated surgically 45 cases of cubitus varus in the Seoul National University Hospital, from 1977 to 1981, and the results were as follows: 1. The mild ulnar n. palsy signs were found in 11 cases(24.5%). 2. The supracondylar, closed wedge osteotomy was done through lateral approach and fixed by cross pinning with 2 K-wires. 3. The postoperative immobilization must be more complete, and the average duration of immobilization was 7 weeks. The osteotomy site united in the all cases, and no limitation of range of motion developed. 4. The incidence of postop. ulnar nerve palsy was the same in the osteotomy only group as in the osteotomy and ulnar n. transposition group. The osteotomy and ulnar n transpositin group recovered naturally, but 2 cases of the osteotomy only group did not recover so ulnar n. transposition was performed later. 5. There was no recurrence of deformity after the average follow-up of 2.2 years, so it was recommended that the correction of deformity should be done in the early childhood.