A simple and selective liquid chromatography-tandem mass spectrometric method for determination of valtrate in rat plasma was developed in this study. Chromatographic separation was achieved on a Thermo BDS HYPERSIL C-18 column using acetonitrile-water-formic acid (75 : 25 : 0.1, v/v/v) as mobile phase in an isocratic mode of elution at a flow rate of 300 mu L/min. MS-MS detection was performed in a positive ion electrospray ionization mode with the ion transitions 445.2 -> 219.2 for valtrate and 355.2 -> 135.1 for internal standard (sesamin). The developed method exhibited a linear dynamic range over 5.65-1695 ng/mL for valtrate in rat plasma. The overall extraction recovery of valtrate from plasma was 86.13-88.32%. The intra- and inter-day accuracy and precision were within the pre-defined limits of <= 15% at all concentrations. The method was successfully applied to pharmacokinetic studies of valtrate in rats.