This study was attempted to investigate the acute toxicity in mice, the subacute toxicity in rats of Cynanchi wilfordii Radix extract, the effect on transaminase activities, hematological parameters, leukocyte parameters in serum of subacute-toxicated rats. In acute toxicity test, the death rate was not observed in 50, 100, 200, 300 mg/kg(i.p.), one tenths to two tenths in 300, 500, 1000, 1500 mg/kg(p.o.) for two weeks. In subacute test, rats were all died in 300 mg/kg(p.o.) during 4 weeks, in 500, 1000 mg/kg(p.o.) during three weeks. The cause of death believed to be stomach ulcer. The activities of S-GOT and S-GPT were significantly increased in all sample-treated groups, when compared with the normal groups. A number of WBC and neutrophil belong to hematological parameter were significantly increased, lymphocyte was decreased in all sample-treated group, when compared with normal group. The hemolytic action on water extract, saponin and alcohol extract showed very low activities.