In athletes, anterior cruciate ligament (ACL) reconstruction is recommended after injury to restore the normal knee function and allow subsequent return to sport. Successful ACL reconstruction with patellar tendon (PT) and hamstring tendon (HT) grafts combined with a well-structured rehabilitation program could bring athletes back to their previous level of sport activities. We prospectively followed-up 100 athletes who underwent ACL reconstruction with either PT (n=50) or HT grafts (n=50). Evaluation was done pre-operatively and post-operatively (3, 6, 12, and 24 months) using International Knee Documentation Committee (IKDC), Lysholm, Noyes, and Tegner scales. Subjective assessment numeric evaluation (SANE), knee activity rating scale (Marx) and a psychological profile questionnaire (psychovitality) were also utilized. Objective evaluations included isokinetic tests and computerized knee motion analysis. Data gathered were statistically analyzed using the Mann-Whitney non-parametric U-test. Among the 100 patients who have undergone ACL reconstruction, 65% returned to the same level of sports, 24% changed sports and 11% ceased sport activities. No significant difference (P>0.05) in outcome between PT and HT grafts were observed. No significant differences (P>0.05) were noted between athletes who "returned" to their previous sport and those who "did not return" to sports at the same level when using the IKDC, Lysholm, Noyes, and Tegner knee evaluation scales. However, significant difference was observed with the knee scores obtained by those who returned and those who completely ceased participation in sport activities. Computerized laxity test revealed that 90% of these patients have less than 3 mm side-to-side difference with no significant difference between HT and PT groups. Patients who "returned to sports" obtained significantly better scores with the Marx scale (P=0.001) and the psychovitality questionnaire (P=0.001) than those who did not. Conventional knee scales including IKDC, Lysholm, Noyes, and Tegner remain as reliable means of evaluating outcome of ACL reconstruction. However, the data obtained from these are not sufficient to determine which among the patients who had knee reconstruction can successfully return to sport. The use of the Marx knee activity rating scale and the evaluation of the athletes' psychological profile are additional scales that can be useful in determining which among the patients treated have a better chance of returning to their pre-injury activity levels.