The supracondylar fracture of the humerus is the most common fracture of the elbow in children, and is occasionally associated with significant residual complications such as cubitus varus deformity. Accurate reduction without additional trauma and good maintenance are essential, in the treament of the supracondylar fracture. A clinical analysis was performed on 20 patients with displaced supracondylar fractures of humerus, who were treated either by closed reduction and percutaneous pinning (10 patients) or by open reduction (10 patients). The results were as follows; 1. The average age of the children was 7 years old in both sexes, and male to female ratio was 2.3: l. 2. Of all fractures, 95% was the extension type, and the left side was more frequently involved. 3. According to Gartland classification, type II was 4 cases, type IIIA was 12 cases, type IIIB was 4 cases. 4. There was no significant difference in the mean duration of bony union between the percutaneous group and the open reduction group. 5. Cubitus varus deformity and limitation of elbow motion were more common in open reduction.