We investigated the effects of creatine (Cr) supplementation on muscle strength and body composition during 13 weeks of training in female collegiate soccer players. Fourteen athletes were randomly assigned to receive either Cr supplementation (7.5 g, 2 times a day for 1 week and 5 g per day thereafter) or placebo dissolved in a fluid-replacement beverage. Baseline measurements were made 1-2 weeks before and at 5 and 13 weeks after beginning supplementation. The Cr group demonstrated greater improvements in bench press and full-squat maximal strength (the trial by group interaction) compared with the placebo group, which were significantly different between baseline and 5 weeks for the bench press and between 5 and 13 weeks for the full squat. Fatand bone-free lean masses measured by dual-energy x-ray absorptiometry increased with training (main effect) but were not enhanced by Cr supplementation. These results suggest that female soccer players increase strength as well as lean tissue during off-season training. Cr supplementation, however, appears to be associated with significantly greater increases in muscle strength but not lean tissue.