Abstract: A sensitive and rapid high performance liquid chromatographic method has been developed for the determination of ipriflavone in human serum. The average recovery of ipriflavone was 85% with relative standard deviation of 3.8%～5.4%. The calibration curve was linear in the range from 8 ng·ml^-1 to 400 ng·ml^-1 with γ=0.9981. The detection limit of the method was 3 ng·ml^-1 (S/N≥3). The serum drug concentration-time curve exhibited a 2-compartment model and the mean T_1/2β was 12.00±1.89 h (for ipriflavone made in Japan) and 9.05±0.80 h (for ipriflavone made in China). The AUC_0→∞ of the two kinds of ipriflavone were 804.99 ng·h·ml^-1 and 807.40 ng·h·ml^-1, respectively. The relative bioavailability of ipriflavone made in China vs that made in Japan was 1.003.