The single dose toxicity of Hwangiaegongjinbo, an invigorator developed by Korea Medical Science Institute was evaluated in ICR mice and Sprague-Dawley rats. The aqueous solution of freeze-dried powder of Hwangiaegongjinbo or its original solution was once administrated orally to both sexes of mice and rats at dose of 2000 mg/kg, the recommended upper limit dose for acute toxicity. Water was administered to another group as control. after single adminstration, sign of toxicity were observed every hour for the first 6 hours and every day for 14 days. Neither sign그cant toxic sign nor death was observed during the observation period. In addition, no pathological changes were noticed in macroscopic examination at necropsy in those treated group. These results indicated that $LD_{50}$ of Hwangiaegongjinbo is greater than 2000 mg/kg in ICR mice and Sprague-Dawley rats.