Electrical stimulation of the lateral septum results in a transient cardiodeceleration which may represent parasympathetic rebound to a brief sympathetic activation. Kainic acid (KA) is a potent neuronal excitant. Stimulation of the lateral septum by KA produced a short-latency tachycardia. Vehicle injections, as well as KA administration to adjacent structures, did not effect significant changes in heart rate. Intraventricular KA, however, did result in a significant tachycardia. Knife cuts of the fornix, interrupting the glutamatergic innervation of the septum, completely blocked the cardiovascular response to KA. Pharmacological treatments reducing sympathetic activity prevented or reversed KA-elicited tachycardia. Thus, it appears that septal administration of KA produces sympathetic activation. KA may serve as a useful tool in studies assessing central regulation of the autonomic nervous system, and the interrelationship between autonomic activity and seizure-induced neuronal loss.