Eupatorin, a bioactive compound extracted from Java tea (Orthosiphon stamineus), possesses potent anti-cancer, anti-inflammatory and vasodilation activities. To date, no pharmacokinetics studies on eupatorin have yet been performed. Here, we established and validated a sensitive and selective LC-MS/MS (liquid chromatography-tandem mass spectrometry) approach for determining plasma eupatorin in rats. Chromatographic fractionation was conducted on a Wonda Cract ODS-2 C18 Column (4.6 mm x 150 mm, 5 mu m) with a mobile phase containing aqueous 0.1% formic acid and acetonitrile using a flow rate of 0.8 ml min(-1). In multiple reaction monitoring mode, precursor-to-product ion transitions for quantification of eupatorin and the internal standard were set at 343.1 -> 328.1 and 252.0 -> 155.9, respectively. The intra- and inter-day precision and accuracy were found to be below 6.72% and within +/- 8.26% in rat plasma, respectively. Meanwhile, all values of the matrix effect, recovery and stability were within the accepted ranges. Furthermore, we carried out the pharmacokinetic analysis using the developed method. The pharmacokinetic study revealed that while theC(max)(maximum plasma concentration) of eupatorin and time for reaching theC(max)(T-max) were 974.886 +/- 293.898 mu g L(-1)and 0.25 h, respectively, the half-life was 0.353 +/- 0.026 h. This study will be of great significance to the research on the pharmacology, clinical pharmacy and drug action mechanism of eupatorin.