Acute toxicity of EPO(Erythropoietin) was investigated using rats and beagle dogs according to Established Regulation of Korean National Institute of Safety Research (1994. 4. 14). Rats and beagle dogs were injected intravenously with dosages of 20000 IU/kg, 2000 IU/kg, 200 IU/kg, 20 IU/kg and 2 IU/kg. In animals injected with EPO, there were neither dead animals nor significant changes of body weights. In addition, no differences were found between control and treated groups in clinical signs and autopsy findings. Therefore $LD_50$ of EPO was considered to be higher than 20000 IU/ kg B. W. in rats and beagle dogs.