1. Objectives: The aim of this study is data analysis for acute toxicity and safety of Cheongsimyeonja-tang. 2. Methods: We investigated the acute toxicity for water-extracted Cheongsimyeonja-tang. Fifty five male and female mice were observed for 14 days after one day oral administration of Cheongsimyeonja-tang at the respective doses of 0 (control group), 2560, 3200, 4000 and 5000 mg/kg. 3. Results: We observed survival rates, general toxicity, change of body weight and autopsy. In animals administered with Cheongsimyeonja-tang, there were nither dead animals nor significant changes of body weights. In addition, no differences were found between control and treated groups in clinical sign and autopsy. 4. Conclusion: The data confirmed that Cheongsimyeonja-tang is free from the toxicity and safety problems in treated groups. Compared with the control group, we could not find any toxic alteration in all treated groups(2560, 3200, 4000 and 5000 mg/kg). Lethal Dose 50 (LD50) value for mice was more than 5000 mg/kg per oral for both male and females. It suggest that Cheongsimyeonja-tang in mice is considered to be safe.