It appears that with an isolated PCL injury, the functional result may be quite good. However, degenerative changes have been found even after these isolated injuries. Pain is usually the predominant feature of the PCL injury. Dandy and Pusey reported that 70% of the patients complained of pain at a seven year follow-up examination. There are controversy in isolated laxity in PCL reconstructive surgery. Our purpose is to review the results of PCL reconstruction with autogenous patellar tendon (Group I) and PCL reconstuction with autogenous patellar tendon plus synthetic polyethylene terephtalate (Trevira ligament, Group II); the result of isolated substance tear of PCL. We followed-up for more than one year. There were 12 cases in Group I and 14 cases in Group II. Among them, isolated PCL injuries were 3 cases in Group I and 5 cases in Group II. By MOller scoring, in Group I, the results were excellent in one case, good in eight, fair in three. In Group II, they were excellent in four cases, good in eight, fair in two. In isolated PCL injury, Group I (three cases) showed two excellent and one good results: Group II (five cases) showed three excellent, one good and one fair results. On posterior stress roentgenograms using Telos stress device, the distance of displacement was measured in the operated and the normal sides, and the difference was calculated. In Group I, there were one case with less than 2mm difference, seven cases with 3-5mm difference and four cases with 6-10mm difference. In Group II, six cases had less than 2mm difference, another six had 3 - 5mm difference and two cases showed 6-10mm. From the above results, it is thought that PCL reconstruction with or without augmentation gives good overall results in terms of function and stability. However, augmentation with artificial ligament seems to ensure better static stability by working as an internal splint during the vulnerable period of healing. The reason for that is, in our opinion, that the autograft and the artificial ligament work like two bundles of normal PCL due to their different pathways, thus giving better stability and preventing stress-shielding effect. And also, in isolated substance tear of PCL, the result was good in both groups. Therefore reconstruction seems to be a worthwhile procedure even in isolated PCL tear, in active young patients having much discomfort in daily living.