This study was first conducted to characterize the intravenous and oral pharmacokinetics of magnolin, a major pharmacologically active ingredient of Magnolia fargesii, at various doses in rats. Magnolin was administered to rats by intravenous injection (0.5, 1 and 2 mg/kg doses) and oral administration (1, 2 and 4 mg/kg doses), and serial plasma and urine samples were harvested. Magnolin concentrations were determined by a validated LC/MS/MS assay. After both intravenous and oral administration, the AUCs were linearly increased as the dose increased. Other pharmacokinetic parameters of magnolin (except the V ( ss ) after the intravenous administration) were also independent of the doses. The extent of absolute oral bioavailability ranged from 54.3-76.4% for the oral doses examined. Magnolin was considerably bound to rat plasma proteins and the binding value was constant (71.3-80.5%) over a concentration ranging from 500 to 10000 ng/mL. The pharmacokinetic parameters of magnolin were dose-independent after both intravenous and oral administration. When given orally, magnolin was rapidly absorbed.