INTRODUCTION: The reconstructions of posterior cruciate ligament (PCL) has been increasing because of increased incidence of insufficiency of the PCL and improved surgical skill Arthroscopic operation is known better than open in cruciate ligamet reconstruction in many respects. Arthroscopic PCL reconstruction, especially using hanstring tendon has some benefits. This study is retrospective study analyzing 20 patients treated by arthroscopically assisted PCL reconstruction using hamstring tendon. ALATERIAL AND METHODS: From November 1993 to June 1996, 20 patients with PCL insufficiency had heen treated by arthroscopically assisted PCL reconstruction using double-looped hamstring (semitendinosus and gracilis) tendon by first author. The isometric point was located slightly posterosuperior than anatomic attachment in femur and 0.8-1.0cm below articular margin in tibia. They were confirmed by intraoperative fluoroscopy. The remnants of intact PCL bundle and meniscofemoral ligaments were preserved and added to the graft. They were nineteen men and one women, with a mean age 31.8 years (range, 15-56 years). RESULTS: The results were as follows; 1. The patients were followed from 13 months to 44 months after operation (average 2years and 2months ). 2. Post operative neurovascular irjuries were not found. 3. No revision case was observed and second operations were made in two cases with posterolateral rotatory instability after primary reconstruction. 4. All patient has no symptom of instability after operation. S. At last follow up, Lyshohn knee scores improved from 62 preoperatively to 89 postoperati.vely on average. CONCLUSION: Arthroscopically assisted PCL reconstruction using double-looped hamstring (semitendinosus and gracilis) tendon is easier and less damage than using bone-patellar tendon-bone graft. It preserves intact meniscofemoral ligament, some intact fibers of PCL bundle and quadriceps mechanism. We think it is a effective treatment for PCL insufficiency patients."