Abstract: F30066 caused severe gastro-intestinal irritation and lowered body temperature in normal rabbits. It potentiated both the stimulant effect of cardiazol and the depressant effect of sodium pentobarbital on central nervous system of mice. In isolated rabbit's heart, F30066 decreased the contractility. Experiments on perfused guinea pig lung indicated that F30066 constricted bronchioles. The signs of acute poisoning in rabbits consisted of paralysis of limbs, respiratory depression, and convulsions. One rabbit suffering from acute poisoning exhibited cardiac arrhythmia.