We used a herbal medicine, roots of Rhodiola sachalinensis (RS) to assess whether RS extract can decrease blood ethanol concentrations in rats fed ethanol and if so, to elucidate the mechanism by which RS extract reduces blood ethanol levels. Rats were fed ethanol orally 1 hr after the oral administration of various doses of RS extract. In another experiment, rats were injected intraperitoneally with ethanol following the intake of RS extract via gastric catheter to eliminate possible inhibition of ethanol absorption in the gastrointestine by RS extract. The administration of RS extract remarkably lowered blood ethanol levels in a dose-dependent manner in rats given ethanol orally. However, the intake of RS extract did not reduce ethanol levels in rats injected with ethanol intraperitoneally. The activities of two main hepatic enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), involved in ethanol metabolism, were not affected by the administration of RS extract in rats fed ethanol. In addition, the intake of RS extract reduced serum triglyceride levels elevated by ethanol to the normal level. We conclude that the administration of RS extract lowers blood ethanol concentrations by inhibition of ethanol absorption in the gastrointestinal tracts of ethanol-fed animals.