High tibial osteotomy has been widely accepted as a method of treatments for middle-aged varus osteoarthritides with uncompartmental involvements. There have been several reports regarding the managements of fibula and their complications during the valgization procedure of tibia. They are, for example, osteotomy of fibular diaphysis or neck and excision of fibular head. Each level of fibular management is often complicated by nonunison, peroneal nerve palsy and lateral instability respectively. We have reviewed 20 cases of cases of high tibial osteotomy using proximal tibiofibular arthrolysis performed between March 1987 and February 1993. This method has proved excellent exposure of upper lateral tibia for the wedge removal, internal fixation and relief of the tethering effect of fibula. There was no peroneal nerve palsy relate to this degenerative change of the proximal tibiofibular was 3.4mm(range 1-11mm) and there was neither degenerative change of the proximal tibiofibular joint nor varus instability. In conclusion the arthrolysis of proximal tibiofibular joint can be highly recommended in high tibial osteotomy.