In children, the supracondylar fractures of the humerus are common in elbow region, and often associated with various complications and problems in treatment (ie,Volkmann's ischemic contracture, cubitus valgus or varus deformity, rotational deformity). The results of reduction can be measured by Baumann's angle, carrying angle, trochlea-capitellum angle, and displacement of distal radial styloid process on radiological study. So we have made experiments on the process which various three dimensional displacements reflected into two dimensional Baumann's angle and humerocapitellar angle. And we investigated the process of rotation, through various radiological studies by means of molded models of humerus. The results were as follows:l. In experiments, AP & lateral X-ray studies showed no change in rotation of proximal segment of fracture with fixed distal segment of fracture. 2. On the other hand, AP & lateral X-ray showed significant change, in rotation of proximal fracture segment with distal segment of fracture. 3. Supracondylar rotation angle(S.R.A.)depicted as the ratio of the length of proximal fracture width minus that of the distal fracture width in lateral view, to the length of distal fracture width in AP view minus that of the distal fracture width in lateral view. 4. According to the modified Mitchell result, S.R.A. to the result of treatment was average 7.6 degree in excellent group, 15.2 degree in good group and 29.3 degree in unsatisfactory group.