The purpose of this study was to investigate the risk factors regarding anterior cruciate ligament (ACL) reconstruction using autogenous semitendinosus tendon by subjective evaluation of the patients. We studied 63 patients who had been followed for 18 months or longer after surgery. They comprised 31 men and 32 women aged 15–45 (mean, 25.5) years. The patients were divided into two groups by subjective scores. Subjective clinical evaluation was performed using 100 mm visual analogue scale (VAS). In the high score group (group H), the VAS score was 80 mm or higher, and in the low score group (group L), the score was less than 80 mm. Forty three patients were in group H and 20 patients were in group L. The parameters examined were age, gender, sports activity level, preoperative period, complicated meniscus injury, articular cartilage status, graft tendon size, joint stability, and knee extension muscle strength.There were 26 men and 17 women in group H, and 5 men and 15 women in group L. There were significantly more women in group L (p<0.01). The mean preoperative period after injury was 23±38 months in group H, and was 52±67 months in group L (p<0.05). The average side-to-side differences in anterior laxity were 1.3±1.0 mm in group H and 2.2±1.6 mm in group L (p<0.01). There were no significant differences in other parameters between the two groups. In this study the risk factors for poor subjective outcome following hamstring ACL surgery was female gender and prolonged delay from injury to operation.