The purpose of this study was to investigate the effects of blood flow restriction therapy on peak torque and work per repetition of thigh muscle. Twelve healthy male college students free of knee problems were enrolled in this study voluntarily. Muscle strength(60deg/sec of knee extension and flexion) of each participant was assessed by the isokinetic dynamometer under three conditions: (1) without blood flow restriction; (2) blood flow restriction of 100mmHg; (3) blood flow restriction of 200mmHg. The results were as follows. There were significant differences in means of peak torque of knee extension and flexion in the all comparisons(0mmHg vs 100mmHg, 100mmHg vs 200minHg, and 0mmHg vs 200mmHg). However, no significant were found in the comparisons of the work per repetition both in extension and flexion. The results indicate that blood flow restriction could help increase muscle strength.