In pediatric ages, the supracondylar fractures of the humerus are common and often associated with complications. In these days, the serious complications were reduced with a lot of apprehension for the treatment. While the fracture itself was healed properly, the remained deformity was frequent and it was known that this deformity was derived not from growth disturbance after fracture but from inaccurate reduction at the time of initial reduction. We have performed an anatomical study. Identical skeletal models were osteotomized at the supracondyle of the humerus and every combination of 0°,10°, 20°, 30° of each of varus, valgus tilt, internal rotation and flexion were tried at osteotomized site and were taken radiography and photographed. We measured T-C angle, carrying angle and displacement of distal radial styloid process on X-ray. We got the results as follow. 1. Simple rotational deformity of 50° have resulted in only 20% decrease of width of distal osteotomized surface in AP films in pure rotational deformity. 2. Flexion at the osteotomized site have no specific effect on the change of varus and valgus deformity. There were remarkable increase from 0° to 20° after then the changes were decreased in varus tendency according to internal rotation. 3. Among the changes of varus and valgus angle, the varus deformity was largest at the change of angle from 0° to 10° and other change of angle of varus and valgus deformity were incrersed at similar degree. 4. At the osteotomy site, without changes of varus and valgus angle, it showed that internal rotation resulted in varus defromity.