The knee is the most frequently injured joint because of its anatomic structures, exposure to external forces and functional demands placed on it. The treatment of the injured knee is not simple due to its complex mechanism in function. There have been a lot of continous research and controversies on the management of injured posterior cruciate ligament out of diverse injuries of the knee. From January 1984 to December 1991, in National Police Hospital among 25 patients with old posterior cruciate ligament injury, 21 cases were followed for more than 1 year after its reconstruction with the medial gastrocnemius tendon. The results were evaluated as good in 18 cases and fair in 3 cases according to Hughston criteria. We concluded that favorable result was obtained from reconstruction of old PCL injuries with the medial gastrocnemius tendon.