Abstract: The total flavone of Ku-shen (TFK) was isolated from radix of Saphore flavescens Ait. which coutains about 0.3% of flavones. The LD 50 of TFK in mice injected intravenously was found to be 103±7.66 g/kg.Albino mice weighing 25～30 g were exposed to chloroform to induce, ventricular fibrillation by the method of Lawsons. The Ventricular fibrillation occured in 80% of the saline treated controls. After intravenous injection of TFK the incidenece of ventricular fibrillation produced by chloroform was significantly reduced. Its ED 50 was found to be 28.9±1.1 g/kg and the therapeutic index 3.56. Under the same experimental conditions the therapeutic index of quinidine sulfate was found to be 2.89.The arrhythmia induced by chloroform-adrenaline in rabbits could be significantly reduced by prior treatment with TFK. The effect occured 30～60 minutes after intravenous injection of TFK at the dosage of 8 or 30 g/kg. The complete inhibition rate was 40% and 70% respectively.The arrhythmias induced by intravenous injection of aconitine in rats may be effectively decreased by intravenous injection of TFK (20～40 g/kg). In two experiments, the efficacy of TFK was 63% and 84% respectively. Intravenous injection of TFK 30 and 60 g/kg in anesthetized rats produced significat negative chronotropic, negative automatotropic and negative dromotropic effect. These effects increased with dosage.