Objectives : This study was carried out to investigate the acute toxicity and safety of Leejung-tang(Lizhong-tang) and fermented Leejung-tang(Lizhong-tang) extract.Methods : To evaluate their acute toxicity and safety, 0(control group), 1250, 2500 and 5000 ㎎/㎏ of Leejung-tang(Lizhong-tang) and fermented Leejung-tang (Lizhong-tang) extracts were orally administered to 35 male and 35 female ICR mice. After a single administration, we observed survival rates, general toxicity, changes of body weight, and autopsy. Results : Compared with the control group, we could not find any toxic alteration in any of treated groups (1250, 2500 and 5000 ㎎/㎏).Conclusions : LD50 of Leejung-tang(Lizhong-tang) and fermented Leejung-tang (Lizhong-tang) were over 5000 ㎎/㎏ and it is very safe to ICR mice.