The contractile properties of the rabbit tibialis anterior muscle were studied 48 hours after an ischemic episode induced by pneumatic tourniquet compression of the thigh. Forty animals were divided into five groups, each of which had continuous ischemia of either 1, 2, or 4 hours, or a total of 2 or 4 hours of ischemia interrupted by 10 minutes of reperfusion at 1-hour intervals. Contralateral limbs served as controls. Muscle contractile properties were tested by stimulation of the peroneal nerve distal to the site of tourniquet compression. Peak tetanic tension in the 1-hour group did not differ significantly from controls. In the 2- and 4-hour groups, peak tetanic tensions were 31% and 2% of controls, respectively, and twitch tensions were 25% and 1% of controls, respectively. Hourly reperfusion intervals had no significant effect on maximum tetanic or twitch tension compared with continuous ischemia for either 2 or 4 hours. Clinically significant muscle dysfunction may be induced by 2 or more hours of pneumatic tourniquet application. Hourly reperfusion intervals may not improve skeletal muscle function distal to the tourniquet. However, reperfusion intervals could still affect muscle that is compressed beneath the cuff. Tourniquet-induced contractile deficits may interfere with postoperative functional recovery.