PURPOSE: This study compared the changes in the range of motion (ROM ) on the knee joint according to three different isometric contraction intensities when applying Evjenth - Hamberg stretching (EHS) to the hamstring muscles of healthy subjects. METHODS: Forty eight healthy subjects aged between 20 and 39 years were allocated randomly to four groups; performing EHS at 10% maximum voluntary isometric contraction (MVIC) group, EHS at 50% MVIC group, EHS at 100% MVIC group, and control group (CG) pre-, and post-intervention. The flexibility of the hamstring muscles was evaluated using a digital goniometer for measuring the knee joint ROM motion. A Chattanooga stabilizer was used to adjust the MVIC intensity by 10%, 50%, and 100%, respectively. RESULTS: These results show that the pre- and post-intervention knee joint ROM were significantly different in all four groups (p<.05). The post-intervention knee joint ROM showed a significant difference between the 100% MVIC group and non-MVIC group (p<.05). The knee joint ROM difference between the pre- and post-interventions was similar in the 10% MVIC and 50% MVIC groups but significant differences were observed among the other groups (p<.05). CONCLUSION: EHS of the hamstring muscles was effective in improving the knee joint ROM with an isometric contraction intensity of 10%, 50%, or 100% MVIC, and of these, 100% MVIC was most effective.