Socheongryong-tang has been used for the treatment of inflammatory allergic diseases such as allergic rhinitis and bronchial asthma in Asian countries. This study was conducted to investigate the safety of Socheongryong-tang in rats. The safety of this tang on acute toxicity was evaluated by single dose toxicity study. Rats were orally administrated in a single dose of 0 and 2000 mg/kg (limited dose) Socheongryong-tang. There were 7 rats in each groups. All animals were sacrificed after 14 days of treatment. After single administration, mortality, clinlcal signs, body weight changes and gross pathological findings were observed for 14 days. Three parameters were tested: organ weight measurement, clinical chemistry, and hematology. In this study with rats, Socheongryong-tang treatment did not show any acute toxicity. No mortality was noted for 14 days of treatment. There were no adverse effects on clinical signs, body weight, organ eight and gross pathological findings at all treatment groups. The clinical chemistry parameters attesting to liver and kidney functions as well as the hematological parameters were within the normal ranges. From single dose toxicity study with rats, it is considered that $LD_{50}$ of Socheongryong-tang is over 2000 mg/kg in oral administration. This finding of the safety on single dose toxicity study of Socheongryong-tang are expected to strengthen the position of Socheongryong-tang as nontoxic medicine.