We report our series of the Ilizarov surgery for lengthening and deformity correction in upper extremity at the Severance Hospital and the Yong-Dong Severance Hospital between February 1992 and October 1994. We performed the Ilizarov surgery in 12 limb segments, there were 3 humerus, 5 radius, 3 ulna and 1 metacarpal bone. The etiologies of the limb length discrepancies were 7 posttraumatic physeal injuires, 2 congenital deformities, 1 posttraumatic bone loss, 1 posttraumatic amputation and 1 postinfectious physeal injury. The goals of treatment were bone lengthening alone in 8 cases, bone lengthening and deformity correction including angular correction in 4 cases. The bone was lengthened between 1.0 cm and 9.2 cm (mean 3.7 cm) representing a 8.1% to 63.0% (mean 24.5%) increase in length. The healing index varies from 1.0 mos/cm to 10.5 mos/cm (mean 3.4 mos/cm) except three cases which need additional fixation with plate and screws add to wedge osteotomy. By radiologic appearance of the distraction callus, the straight type were 6 cases, the attenuated type were 4 cases and the pillar type were 2 cases. The healing indices of each type were 1/5 mos/cm, 7.7 mos/cm and 12.4 mos/cm, respectively. In conclusion, lengthening and deformity correction of the upper extremity can be successfully achieved by gradual mechanical distraction using the Ilizarov method. In case of pillar type, healing index was high and therefore control of the rate and the rhythm should be tried. If this control is of no use, early interventional procedure would be beneficial. The healing index of the straight type was much lower than that of the attenuated or the pillar type.