This study was carried out to examine the safety of Coccimuel-S, an anticoccidiol, using male and female ICR mice. Mice were orally administered Coccimuel-S at dose levels of 250, 500, 1,000 and 2,000 / body weight for singledose toxicity test. There were no significant differences in change of body weight between control and all groups treated with Coccimuel-S. Also, general toxic symptoms, clinical signs and mortality were not observed. In the hematological analysis, none of the parameters were affected by Coccimuel-S. This suggests that there are no negative effects on homeostasis and immunity. In blood biochemistry analysis, none of the markers were affected by administration of Coccimuel-S. Similarly, there were no significant effects on markers for liver, kidney, skeletal and heart muscle functions in all treated-groups. No remarkable lesions were detected in these organs with macroscopic examination. Since there were no adverse effects of Coccimuel-S in single oral toxicity tests, even at higher doses than normal, it was concluded that Coccimuel-S could be candidates as a safe anticoccidials for the treatment of poultry coccidiosis.