Closed interlocking nailing has become a common method of treatment of femoral fractures in adults. Interlocking nailing had a tendency toward rotational deformity and shortening. Therefore, we determined anteversion of the femoral neck after closed IM nailing of the femoral fractures. Femoral rotational deformity in both leg was determined by the construction of a line through the femoral neck and another through the transcondylar plane of the distal portion of the femur, using the CT scanning. We performed a retrospective study of 15 patients treated with closed IM nailing for femoral shaft fractures from 1989 to 1994. 1. The average differences in anteversion angle was 12.9 degree. 2. 3 cases(50%) in 6 cases that have difference more than 15° are accompanied with ispilateral injury of the knee joint and the lower leg. 3. Angle difference of the rotational deformity of proximal or distal femoral fractures is 15.5° which is 3.5° larger than that of fractures of femoral midshaft, 12.0°.