Recent studies have suggested that acute static stretching (SS) decreases muscular strength and performance, particularly of the knee extensors. The purpose of this study was to investigate the effect of SS on peak concentric and eccentric torque production in the knee flexors. Subjects (13 women and 16 men) were tested for isokinetic concentric (CON) and eccentric (ECC) peak torque at 2 velocities (60 and 210 degrees x s(-1)) before and after a 3-minute knee flexor SS protocol. Subjects also underwent a control day in which the isokinetic pre- and posttests were separated by 10 minutes of sitting rather than stretching. A sit and reach test was administered on both days to assess changes in flexibility that occurred as a result of the stretching or control protocols. The change in flexibility was significantly greater after stretching than after sitting. Changes in peak torque were not significantly different between the stretching and control conditions for either velocity or contraction type. Compared with the control condition, SS of the knee flexors before maximal isokinetic testing does not lead to significantly diminished CON or ECC torque output at slow or fast contraction velocities. These data suggest that moderate SS does not impact the performance of all muscle groups.