Autonomic hyperreflexia is a condition which may occur in individuals with spinal cord injuries above the splanchnic sympathetic outflow. Noxious stimuli can produce profound alterations in sympathetic pilomotor, sudomotor, and vasomotor activity, as well as disturbances in cardiac rhythm. A case of autonomic hyperreflexia in a patient with C6 tetraplegia with recurrent ventricular fibrillation and cardiac arrest illustrates the profound effects of massive paroxysmal sympathetic activity associated with this condition.