Global cerebral hypothermia of 24 degrees C was induced without systemic cooling by means of selective hypothermic perfusion of a single internal carotid artery in four baboons. With a closed-circuit pump system, blood was withdrawn from the femoral artery, cooled in a water bath, and infused through an internal carotid artery catheter, which was positioned with fluoroscopic guidance. This endovascular technique may have applications in the treatment of neurologic disease in humans.