Abstract: Objective To determine acute toxicity reactions and approximate lethal dose of the anti-tumor drug of Chelerythrine.Methods The drug toxicity and side effects were observed when the mice,rat and canine were treated according to toxicological procedures of safety evaluation for drugs.Results The animals were quiet and unanimated,breath was deep and slow,its fur was thin and lackluster;the rats were not sensitive to feeble stimulations.The dead animals were anatomized and abnormal changes were observed:liquid with blood cells in thorax,tumescence of many organs with congest and ecchymosis.A delayed bleeding time was observed in the pinhole of tail vein.Symptoms of celiac stimulation were also observed in rats,included the wring reaction and breadthwise welter.The median lethal dose(LD₅₀)was 22.84mg/kg for mouse iv and 24.30mg/kg for rats ip.Approximate lethal dose was 19.94mg/kg for Beagle canine iv.Conclusions The drug on animals have significant toxicity,the cause of death related with the liquid into the blood caused by vascular dilation,congestion,multiple organ blood circulation disorders,acute respiratory failure caused by respiratory disorders and direct stimulation of abdominal organs.