Abstract: Berberine(Ber) (1mg/kg×3 or 10 mg/kg) given intravenously to conscious rats was shown to decrease BP, LVSP and LVEDP. The magnitude of decrease was in the order of DAP>SAP>LVSP. The HR was first accelerated reflexly and then decreased gradually and persistently. The cardiac contractility as shown by+(dp/dt)max,(dp/dt) p^-1 and LVP-(dp/dt)/P^-1 loop were not diminished and even augumented, in spite of the concomitant decrease of after load and heart rate. The above results indicate that Ber has positive inotropic and negative chronotropic actions on the heart, while its hypotensive effect is mainly due to lowering of total peripheral resistance in addition to slowing of heart rate.