Experiments were performed on anesthetized cats to observe the effect of electrical stimulation of the hypothalamic ventromedial nucleus (VMH) on cardiac contractility as judged by the change in LVSP, dp/dtmax, Vmax, P-dp/dt, P-lndp/dt. Electrical stimulation of VMH induced an augment response in cardiac force, while stimulation of an area between VMH and the third ventricle led only to a decrease in cardiac contractile force. All these changes were not accompanied by significant changes in heart rate and unaffected by bilateral vagotomy. The present experiment indicates that the inotropic and chronotropic regulation centers of cardiac function exist in different hypothalamic areas.