In recent years, in Vietnam, many poisonings of the plant Cryptolepis buchananii have been reported. Effects of this plant on human body have not been adequately studied. This study was conducted to identify its toxicity on experimental animals. Results showed that: oral LD50 in mice was 0.324g/kg body weight, LDmin in rats was 0.3lg/kg and in rabbits was 0.356g/kg. Heart rate, maximum and minimum blood pressure increased 1 hour after poisoning, but after 6 hours and 24 hours the maximum and minimum blood pressure decreased in comparison with that before poisoning. Extracts of Cryptolepis buchananii dried leaves in the concentration of 1.2 percent caused frog heart stop beating. Serum AST, ALT activity and white blood cells increased with statistical significance in comparison with before poisoning. Changes of other biochemical and hematological criteria had no significance.