The purpose of the present study was to investigate whether duration of static stretching could affect the maximal voluntary contraction (MVC) and flexibility of hamstring muscles. 10 male physical education students randomly performed three warm-up protocols on different days. The protocols included: a) five minutes of treadmill run and 45 seconds (3×15 seconds) of static stretching of hamstring muscles, b) five minutes of treadmill run and 90 seconds (3×30 seconds) of stretching, c) five minutes of treadmill run (control condition). In each session, before and after each protocol, hamstring flexibility was measured by a sit and reach test and then MVC of hamstring muscles was measured. The results showed that hamstring flexibility significantly increased after 3×15 and 3×30 seconds of static stretching (p<0.05); however, there was no significant difference between the two stretching protocols (p>0.05). The MVC significantly decreased after 3×30 seconds of static stretching compared to the control and 3×15 seconds of protocols (p<0.05). However, there was no significant difference between control and 3×15 seconds of static stretching conditions (p>0.05). Therefore, it was concluded that the short duration (3×15 seconds) of static stretching did not have a negative effect on the production of muscle force.