Abstract: The LD₅₀ in mice was found to be 38.5g/kg for the infusion of Kwang-Ti-lung, given by intravenous injection. The infusion has been orally administered to rats (0.1g/kg/day) for 45 days without any toxic effect. The infusion and extract with 70% alcohol by intravenous injections to anaesthetized dogs (0.1g/kg) or by oral administrations to normal rats (10g/kg) produced a fall of blood pressure. This hypotensive effect might last for 2—3 hours. Ten renal hypertensive rats were treated with the extract at a dosage of 0.1 g/kg/day. The drug was given to all the rats for 2 weeks by oral administration. Hypotensire effect in most rats was observed in 3—7 days after medication, and became more remarkable in the second week of the therapeutic period or the first week after cessation of medication. The blood pressure in most rats returned in 2 weeks, and some rats in 4—5 weeks after the stopping of medication. The fall of blood pressure produced by Kwang-Ti-lung was neither due to the effect of the vagus, nor due to the direct dilatation of the blood vessels and the blocking of the ganglia of the vegetative nerves. The mechanism of its hypotensive effect is thought to be chiefly due to the dilatation of splanchnic vessels produced by the direct or reflex effect of Kwang-Ti-lung on the central nervous system above spinal cord.