We studied 30 patients who participated in accelerated rehabilitation program after ACL reconstruction to evaluate the effects on knee joint function prospectively. This program emphasizes early full hyperextension, early weight bearing as tolerated, and closed-chain quadriceps functional activities with rapid return to sports. Timing of the return to occupation, activity level, manual knee test, range of motion, thigh circumference, Lysholm knee score and KT-2000 arthrometer measurement were checked at the latest follow-up which is at least more than 1 year. The result were as follows: 1. The mean time for patients to return to occupation was 7.5 weeks (2 weeks-6 months). 2. Range of motion of the knee were not limited in 25 cases (83%) at 1 year after reconstruction. 3. The mean Lysholm score was 92.7. 4. The mean manual maximum KT-2000 arthrometer score was 2.0mm. The results of this study show that patients who had an ACL reconstruction with an autogenous central 1/3 patellar tendon graft and followed an accelerated rehabilitation program obtained longterm stability, achieved full range of motion, had a low complication rate, and were able to return to full sporting activities predictably.