Kami-Okchun-San(OCS) is known as an effective herbal medicine on Type 2 diabetes. We peformed to investigate acute toxicity of OCS on ICR mice. ICR mice in acute toxicity experiment were administered orally with dosages of 3,200mg/kg (low dosage group), 4,000mg/kg (middle dosage group), 5,000mg/kg (high dosage group) per single time, respectively. Body weights, clinical signs, motalities and histopathological finding were observed daily for 14 days according to the Regulation of Korean Food and Drug Administration(1999. 12. 22). Single oral administration of OCS with different dosages, no animals died of the test drug. Autopsy of animal revealed no abnormal gross findings. Therefore, LD50 value of OCS for ICR mice was more than 5,000mg/kg on oral route. Normally increasing changes were observed in body weight, drinking water and food intake in every dosage group. Hematological parameters were also observed normally in all animals. No histopathological lesions were observed in both control and treated animals. Above data suggest that no toxic dose level of OCS in ICR mice is considered to be more than 5,000mg/kg. Therefore, it was concluded that OCS have no effect on acute toxicity and side effect in ICR mice.