Though bone-patellar tendon-bone autograft has been succesfully used for the reconstruction of the anerior cruciate ligament, proper protection and guided rehabilitation are needed during the period of revascularization and recollagenation of the graft to prevent lengthening. We experienced a series of 23 reconstructions of the anterior cruciate ligament from November 1989 to May 1991 using bone-patellar tendon-bone autograft reinforced with synthetic polyethylene terephtalate (Trevira ligament) hoping that the artificial ligmaent act as an internal splint during the vulnerable period of healing. Bone-patellar tendon-bone was passed through the transosseous hole in the tibia, then across the knee and through the isometric path of lateral femoral condyle as a bone tunnel. And 6 mm Trevira liganent was passed through the same tibial tunnel and over the top route. Of the 23 cases, 15 cases with follow up were evaluated and the average duration of follow up was 19.2 months(minimum: 12 months, maximum: 30 months). And we lost follow up in 8 cases. According to Muller's criteria, the results were excellent in 5 cases (33%), good in 9 cases (60%) and fair in 1 cases (7%). On stress X-rays by Telos device, the differences of anterior displacement between injured and opposite sioe were decreased from average 9.3mm to 2.6mm. And subjectively, there is no differences between injured and opposite site in 4 cases (27%) of the patients. Postoperatibve complication was Trevira ligmanet rupture at tibial bone tunnel due to retrauma in one case. Although the clinical results of our seies are excellent, further studies on the function and fate of the artificial ligament are required.