Objectives: To evaluate the toxicity of KOB03, polyherbal medicine for the treatment of allergic rhinitis, we performed the dose-range finding test of KOB03 by oral supplementation for 4 weeks in Sprague-Dawley rats. Methods: The water extract of KOB03 consisting of five different herbs was supplied from GLP company. KOB03 was supplemented by gavage at 0, 500, 2,500 and 5,000 ㎎/㎏/day for 4-week consecutive days. We recorded the clinical signs of toxicity, body weight, organ weights, hematology, gross and histological changes in target organs of rats, and clinical chemistry analysis. Results: KOB03 at all doses was shown no mortality or abnormal clinical signs in rats during at the observation period. Furthermore, there was no difference in body weight and food-take consumption, organ weight, gross pathological findings, and urine analysis among the groups of rats treated with different doses of KOB03. The hematological analysis and clinical blood chemistry data were revealed no toxic effects from KOB03-supplemented rats. Conclusions: The results suggest that KOB03 is a wide margin of safety on dose-range toxicity in rats. The no observable adverse effect level (NOAEL) of the test, KOB03 in rats is no less than 5,000㎎/㎏/day.