Forearm venous compliance, venous and arterial pressures, heart rate, and forearm blood flow were measured in adult patients before and at two levels of anesthesia with cyclopropane and halothane. Subjects were not premedicated and observations were made before operation. Cyclopropane anesthesia was accompanied by increases in arterial and venous pressure, and by decreases in forearm venous compliance and blood flow. Halothane anesthesia was associated with decreases in arterial pressure and slight increases in venous compliance, venous pressure, heart rate, and forearm blood flow. The changes in arterial and venous pressure, heart rate and forearm flow observed with both agents are similar to observations reported previously. The decrease in forearm venous compliance found with cyclopropane is attributed to an increase in tone in venous smooth muscle.