The supracondlyar fracture of the humerus is the second most frequent injury next to the forearm bone fracture in childhood. In general, need for accurate reduction and good maintenece is essential for a good and result. From Mar. 1983 to Mar. 1989, one hundred and thirtyone supracondylar fractures were treated at Kangnam St. Mary's Hospital. Nineteen cases with vascular embarrassment (with or without neurologic deficit) and fifty-three cases in whom the conservative manipulative trial more than twice were failured, were treated by open reduction and internal fixation. Among them, forty-one cases who were followed up more than six months, were reviewed retrospectively. The results are as follows:1. Boys were more vulnerable to injury than girls by the ratio of 28:13, and causes of injury were mostly by fall from height (56.1% ) and slip down (41.5%). 2. Peak age of incidence was seven years in both sexes. 3. Postoperative vascular impairment or Volkmann's ischemia were not complicated. Neurologic deficits accompanied with the injury were all recovered completely within 3 weeks to 5 months except one case of ulnar nerve damage. 4. One case of myositis ossificans in flexion type fracture was found on X-ray at 9 weeks after operation but the symptom was unremarkable. 5. Among the 41 cases, accurate reductions were obtained 27 cases, but in 14 cases some degrees (2°-13°) of tilt or angulation (2°-6°) of distal fragment were observed. In the cases of accurate reduction, varus deformity was complicated only in one case (3.7%), but in the cases of inaccurate reduction, varus deformity compicated in 4 (28.5%) cases. The results suggest that residual cubitus varus deformity depends much more on the status of reduction than on the overgrowth of the condyle or premature cessation of the physis, even in the surgically treated cases (open reduction and internal fixation).