PURPOSE: The purpose of this study was to determine the effectiveness of three PNF stretching techniques for improving hamstring flexibility and to compare the effectiveness of three PNF stretching techniques(direct and indirect and mix(direct&indirect) of hold-relax technique). METHODS: The subjects were randomly assigned into three groups: group1-direct-hold-relax technique(n=10); group2-indirect-hold-relax technique(n=8); group3-mix(direct&indirect)-hold-relax technique(n=10). For each group, stretch was performed three times a week for a period of three weeks. Hamstring flexibility for each group was measured using the ASLR and PSLR. RESULTS: The results showed significant improvement in hamstring flexibility for all subjects of three groups. However, were not significantly different between the three groups. CONCLUSION: In conclusion, three PNF stretching techniques are confirmed to be useful for improving hamstring flexibility. The choice for a qualified technique has to be made individually according to patient and therapist.