With the advent of improyed external fixation device, femoral lengthening has gained renewed popularity in recent years in the treatment of unequal leg length. Wagner(1971) and De Bastiani et al(1987), among others, have made epochal contribution in this field. During the period from May 1984 to May 1987, 25 patients with leg length discrepancy underwent femoral lengthening using Wagner's or De Bastianis distractable external fixators at the Department of Orthopedic Surgery, Seoul National University Hospital. There were 6 patients below 16 years of age admitted to the Children's Hospital, and 19 patients were 16 years or older. The mean age was 18.2 years, ranging from 3 years to 36 years. The underlying etiology included residual poliomyelitis in 20 patients, epiphyseal injury in 2 patients, congenital short femur in 1 patient, septic hip residua in 1 patient, and cerebral palsy in 1 patient. The mean leg length discrepancy was 4.5cm, ranging from 1.3cm to 7.4cm. The mean length gained was 4.1cm, ranging from 1.8cm to 6.4cm. All except two patients had two stage procedures with iliac crest strut bone graft. The mean time required for radiological consolidation of bone graft was 4.8 months. The plate and screws used for osteosynthesis was removed after the medullary canal has been re-established. Six patients had removal of the plate and screws between 8 months and 25 months after the second stage osteosynthesis. Technical errors included 1 case of incomplete osteotomy which required manual clasis, and another case of faulty insertion of Schanz screws that required reinsertion. Five cases (33.3%) had the minor pin tract infection. Schanz screw breakage occurred in a case of one stage femoral lengthening. Loosening of plate and screws was seen in three cases. One case had delayed union requiring augmentation bone graft. Stiff knee with less than 90°of flexion was encountered in one case. One case sustained fracture of patella during physiotherapy. Despite of a long list of complication, the ultimate goal of leg length equalization was successfully achieved in all the cases.