The first total hip replacement was designed by Wilis in 1938 and has been usod in Korea for rclief of pain, joint stability and joint motion increase after 1970. The loosening has been one of the most serious problems, such as infection, wearing, and others. To decrease the incidence of the aseptic loosening of the femoral stem, European and/American researched the anthropometrics ot the femurs. From this research, they designed femoral stems for their patients. The authors report an anthropometrical measurement of the proximal femur shaft by an external measuring and Computer-Aided 3 Dimensional reconstruction. The results of these studies were as follows:l. In anthropometric measurement of femur for 20 subjects, mean of the maximum femoral length was 42.58±1.43cm for males, and 38.79±2.5cm for famales. 2. Mean angle of the femoral anteversion was 15.8±9.21 degree. 3. In the study of the anterior curvature of the femur, mean position index was 42.05±4.54% and mean index of bowing was 3.72±1.21%. 4. The mean of the femoral neck-shaft angle was 129.5±5.81 degree. 5. The minimum external cicumferential diameter of the femur measured 12.5cm below the lesser trochanter for males and 15cm below the lesser trochanter for females. 6. In the Computer -Aided 3 -Dimensional reconstruction study for selected 4 femurs 1) In the study of external diameter of the femur, the minirnum transverse diameter was 2.47cm at 15cm below the lesser trochanter, and the anterior-posterior diameter was 2.40cm at 5cm below the lesser trocanter. In the study of internal diameter of the femur, the minimum transverse diameter was 1.39cm at 10cm below the lesser trochanter, and the anteriorposterior diameter was 1.36cm at 7.5cm below the lesser trochanter. 2) The internal circumference of the medullary cavity measured at 15cm below the lesser trochanter was 8.22cm. 3) The minimun area of the medullary cavity measured at 10cm below the lesser trochanter was 1.47cm2. 4) The minimum Inertia was measured at 10cm below the lesser trochanter, and its mean value was 0.18cm⁴.