PURPOSE: We classified patients who underwent arthroscopic anterior cruciate ligament (ACL) reconstruction into six groups according to graft material and age, and clinical, radiological, and second look arthroscopic results were compared and analyzed. MATERIALS AND METHODS: From January 2006 to December 2009, 57 patients underwent arthroscopic ACL reconstruction and second look arthroscopic examination. We divided patients according to graft materials into the autogenic hamstring tendon group (group 1) and the allogenic tibialis tendon group (group 2), and according to age into three groups (A, B, and C). The mean age at follow-up for second look arthroscopy was 34 years old. Fifty four patients were male and three patients were female, and mean follow-up period was 21.8 months. The result was clinically evaluated using a KT-1000 arthrometer under anesthesia, and the subjective and objective score of International Knee Documentation Committee (IKDC), and radiologically evaluated using the Telos(TM) stress test. We observed graft tension, synovialization and gross findings through a second look arthroscopic examination. RESULTS: The clinical and radiographic results in patients in group 1 and group A showed excellent finding, however, no statistically significant difference was observed. Second look arthroscopic examination in group 1 and group A showed excellent finding. In particular, the formation of synovialization showed excellent finding (50% or more synovialization) in 75% of patients in group 1A who were young and used an autogenic tendon graft, and 45% of patients in group 2C (over 50 years old and allogenic graft), and they were significantly different (p=0.046). There was significant difference in that tension of graft was excellent in group 1A (less than 3 mm). Through the IKDC evaluation method, 93% of cases that showed normal formation of synovialization and 50% of cases that showed inadequate formation of synovialization showed 'like normal' abnormality, so that was correlation was observed between synovialization and IKDC evaluation (p=0.001). CONCLUSION: Patients who used autogenic hamstring tendon and who were young showed excellent synovial membrane formation. In the old age group, autogenous graft will be more optimal.