Higenamine is a tetrahydroisoquinoline alkaloid which was isolated as a cardiotonic principle from Aconiti tuber. 1.v. injection of higenamine was reported to increase the cardiac output and heart rate and to decrease the blood pressure and the systemic vascular resistance presumably by stimulating the adrenergic ${eta}-receptors$. The anti-platelet and anti-thrombotic effects of higenamine were investigated in this paper. Higenamine(0.5 mg/ml) showed mild inhibitory effect against collagen induced platelet aggregation in vitro and the inhibito교 effect was increased with the pre-incubation$(5{sim}30;min)$ of platelet rich plasma(PRP) with higenamine. With the 30 min incubation, the platelet aggregation was almost completely inhibited. And the oral administration of higenamine$(50{sim}200;mg/kg)$ enhanced the survival in the mouse model of thrombosis and that of endotoxic shock. The anti-thrombotic and anti-septic effects of higenamine thus appear to be due to the ${eta}-agonistic$ and the anti-platelet effects of this compound.