The pharmacokinetic charactor of ginsenoside Rg₁, one of the main saponins of ginseng (Panax ginseng C.A. MEYER), was investigated in rats by using thin-layer chromatography (TLC) and a dual-wavelength TLC scanner. Ginsenoside Rg₁ was absorbed rapidly from the upper parts of the digestive tract (accounting for 1.9-20.0% of the dose of Rg₁ administered orally). The serum level of ginsenoside Rg₁ reached its peak at 30 min, and the maximum levels of ginsenoside Rg₁ in tissues were attained within 1.5 h. However, ginsenoside Rg₁ was not found in the brain. Ginsenoside Rg₁ was excreted into rat urine and bile in a 2 : 5 ratio. It was also proved that ginsenoside Rg₁ was not significantly metabolized in the liver. However, the decomposition and/or metabolism of ginsenoside Rg₁ in rat stomach and large intestine were confirmed.