The present study was carried out to investigate the potential subacute toxicity of CS682, a fermentation product of Korean soil bacteria, by 3-week repeated oral administration in Sprague-Dawley rats. The test substance was administered once daily by gavage to male and female rats at dose levels of 0,100, 300, and 1,000 mg/kg/day for 3 weeks. During the test period, clinical signs, mortality, body weights, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were examined. Throughout the study period, no treatment-related deaths were observed. There were no treatment-related effects on clinical signs, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, necropsy findings, organ weights, and histopathology in any treatment group. Based on these results, it was concluded that the 3-week repeated oral administration of CS682 to rats did not cause any adverse effects in rats at dose levels of ≤1,000 mg/kg/day. Under these experimental conditions, the NOAEL of CS682 was considered to be over 1,000 mg/kg/day for both sexes. Key words: Feed additive, CS682, repeated dose toxicity, NOAEL, rat