Single-and repeated-dose toxicities of Compound K (CK) were evaluated according to Toxicity Test Guidelines of Korea Food and Drug Administration using Sprague-Dawley rats. For single-dose toxicity study, CK was dissolved in drinking water, orally administered and examined for 14 days. As results, CK up to a dose of 5,000 mg/kg, the limited dose, neither induced death, clinical signs and necropsy findings, nor affected body weight gain and organ weights, in which 10% lethal dose could not be estimated. Based on the results of single-dose toxicity test, CK was administered at doses of 500, 1,000 or 2,000 mg/kg for 28 days for the evaluation of repeated-dose toxicity. All doses including the limited dose (2,000 mg/kg) of CK did not cause any abnormalities of rats, including mortality, clinical signs, body weight gain, feed/water consumption, necropsy findings, organ weights, hematology, blood biochemistry. Rather, high doses (1,000 - 2,000 mg/kg) of CK reduced the serum levels of alanine transaminase (ALT), aspartate transaminase (AST), creatinine phosphokinase (CPK), lactate dehydrogenase (LDH) and triglycerides, in addition to an increase in glucose, indicative of protective effects on hepatic and muscular injuries. Thus, both maximum tolerable dose (MTD) and no observed adverse effect level (NOAEL) were not determined. The results indicate that long-term intake of high-dose CK might not induce general adverse effects.