The acute toxicity of a recombinant human interferon $alpha$A (code name: LBD-007) was evaluated in both sexes of ICR mice, 5 weeks old, by the oral, subcutaneous and intravenous routes of administration. Based on the results, LBD-007 was not considered to induce any toxic effect on the mice in mortalities, clinical findigs, body weights and gross findings. It is suggested that LD$_{50}$ values in mice would be $>48{ imes}10^8$ IU/kg in the oral, subcutaneous or intravenous routes.s.