Four-week toxicity of EPO(erythropoietin) was investigated using New Zealand White rabbits according to the established regulations of Korean National Institute of Safety Research. Rabbits were administered intravenously seven days per week for 28 days with dosage of 0, 80, 400 and 2000IU/kg B. W./day. Animals administered with EPO showed no significant changes of body weight, water consumption and feed consumption, and no clinical signs and death. They were not significantly different from the control group in hematological and serum biochemical analysis, urinalysis, prothrombin time, and partial thromboplastin time. In this study, we concluded that EPO had no toxic effect in the New Zealand White rabbits when they were administered intravenously below 2000IU/ kg B.W./ day for 28 days.