Objective. Previous studies have demonstrated that various factors alter postural stability. Our aim was to examine the effect of plantar flexor fatigue on postural stability in quiet standing. Methods. Fifteen healthy male university students (age, 21.3 ± 1.7y; height, 1.83 ± 0.06m; weight, 81.6 ± 9.4kg) were instructed to stand on a force plate before and after calf fatiguing exercise. The sensory systems were controlled by blindfolding subjects and having them stand on a flat firm surface, without moving their head. Fatigue was achieved through repetitive weighted plantarflexor exercise. Standing balance was assessed by using a force plate to calculate Center of Pressure (CoP) displacement.