The proximal tibial osteotomy is a procedure that usually corrects abnormal tibiofemoral angle in osteoarthritis of the knee. In general, we could corrects tibiofemoral angle in ratio of 1mm wedge significantly by the level of osteostomy and size of tiba in patients. The radiologic measurement of proximal tibia and fibula has not been reported. So we analyzed the knee standing AP and lateral films taaken from the 491 patients during the period from January 1988 to December 1989. The results were as follows. 1. The width of tibial plateau was average 82.24mm. 2. The distance between tibial plateau to fibular head was average 11.41mm. 3. The width of proximal tibia at the level of fibular head was average 78.63mm. 4. The width proximal tibia at distal 5mm, 10mm and 15mm along the lateral margin of tibia from fibular head was average 75.78mm, 72.69mm and 65.10mm each other. 5. The length of second osteotomy line with 10mm wedge thickness from fibular head was average 75.06mm. The length of second osteotomy line with 10mm wedge thickness 5mm below fibular head was average 71.48mm. 6. Authors compared radiologic size of proximal tibia which was checked from 1m distance with true bone size of cadaver and patient, and the ratio was 1.13:1. 7. It was suggested that the radiologic measurment of proximal tibia is advised basic study for development of implant because the conventional implant developed other people was not adapted proximal tibia to Korean.