Abstract: The effects of DMC (dl-demethylcoclaurine, higenamine), an active component of aconitum, on cardiac function of normal and experimental heart failure, as well as isolated failing heart in guinea pigs were studied.The contractile force of the normal heart was increased significantly by intravenous infusion of DMC 2 μg/kg/min for five minutes, as indicated by increases of LVSP and LV dP/dt_max to 58±7 and 26±7% of their initial values respectively. During the heart failure of guenea pigs induced by intravenous injection of sodium pentobarbital, the LVSP and LV dP/dt_max decreased to 40±5.0 and 31±2.8% of normal values respectively, which returned to 79±14 and 75±10% of the normal values after intravenous injection of DMC.The cardiac contraction of the isolated failing heart of the guinea pigs were similarly increased by DMC infusion.