The present study was carried out to investigate the potential acute toxicity of Balbusae caulis in taeniam by a single oral dose in Sprague-Dawley rats. Twenty rats of each sex were randomly assigned to four groups of 5 rats each and were administered singly by gavage at dose levels of 0, 1250, 2500, and 5000 mg/kg body weight. Mortalities, clinical findings, and body weight changes were monitored for the 14-day period following administration. At the end of 14-day observation period, all animals were sacrificed and complete gross postmortem examinations were per-formed. Throughout the study period, no treatment-related deaths were observed. There were no adverse effects on clinical signs, body weight, and gross finding at any dose tested. The results showed that the single oral administration of Balbusae caulis in taeniam did not cause any toxic effect at the dose levels of 5000 mg/kg or lower in rats and the minimal lethal dose was considered to be over 5000 mg/kg body weight for both sexes.