Perfusion of the isolated, rat hind limb was performed during conditions of rest and exercise. The rate of blood flow increased progressively from onset of perfusion in both the control and stimulated preparations with no significant difference between the two groups, whereas glucose disappearance from the perfusate was greatly accelerated during exercise. The exercised limb extracted more glucose from the blood than the control preparation, in spite of a lower glucose concentration and a diminished volume of perfusate passing through the muscle during the same period of time. Glucose uptake remained elevated during the entire period of electrical stimulation of the motor nerves, even though the amplitude of muscle movements gradually diminished with time. 1 This investigation was supported in part by Grant#U-1836 of the Health Research Council of the City of New York.