The purpose of this study was to determine the delayed effects of stretching, both static and PNF, on hamstring flexibility following exercise. Subjects were randomly assigned to one of three groups: PNF on left leg, static stretch on right leg; PNF on right leg, static stretch on left leg; and no stretch. Testing limbs were also randomly assigned. A total of 30 college aged students, 19 males and 11 females, who were healthy and free of current and prior knee, hip, and low back injuries, volunteered for this study. The research design was analyzed with two 3 x 3 mixed factorial ANOVA (treatment groups x testing session). A significant interaction was found for treatment groups x testing sessions for PNF and static stretch from the pretest to the midtest and the pretest to the posttest, as well as for the control group from the pretest to the posttest and the midtest to the posttest. No significant interaction was found for treatment groups x testing sessions in the sit and reach. However, a main effect difference was found between the testing sessions between pretest to posttest, midtest to posttest, and between pretest and midtest.