This study was performed to investigate repeated-dose toxicities of Clean natural, a new disinfectant, in Sprague-Dawley(SD) rats. In the 4-week repeated oral toxicity study, Clean Natural was orally administered once daily via gavage to male and female rats at dose levels of 0, 500, 1,000 and 2,000 mg/kg body weight for 4-weeks. There were no deaths and clinical signs during the dosing period. In both sexes, there were no statistically significant differences between the administered and control groups in urinalysis indicators and hematological parameters. In serum biochemistry, aspartate aminotransferase(AST) was significantly decreased and sodium content was increased in the 2,000 mg/kg male group, while chlorine was significantly decreased in the 2,000 mg/kg female group. Also, albumin, total cholesterol and total bilirubin were significantly increased in the 2,000 mg/kg male and female group. In histopathological examinations, centrilobular hepatocellular hypertrophy in the liver was observed in the 2,000 mg/kg male and female groups. And pigmentation in the spleen was observed in the 2,000 mg/kg male group. In conclusion, four-week repeated oral dose of Clean Natural to rats did not cause apparent toxicological change at the dose less than 2,000 mg/kg body weight. Thus it is suggested that no-observed adverse-effect level(NOAEL) for Clean Natural in rats was considered to be 1,000 mg/kg/day.