Methyl salicylate-2-O--D-lactoside (MSL), a natural salicylate derivative of Gaultheria yunnanensis (Franch.) Rehder (G. yunnanensis), has been shown to provide a beneficial anti-inflammatory effect in animal models. Studies on the pharmacokinetics and bioavailability of MSL can provide both a substantial foundation for understanding its mechanism and empirical evidence to support its use in clinical practice. A simple and sensitive high-performance liquid chromatography (HPLC) method, coupled with ultraviolet analyte detection, was developed for determining the concentration of MSL and its metabolite in beagle plasma. Chromatographic separation was achieved on a Agilent Zorbax SB-C-18 column (5 m,4.6x250 mm). The mobile phase consisted of aqueous solution containing 0.1% phosphoric acid and acetonitrile (82:90, v/v), at a flow rate of 1 mL/min. Validation of the assay demonstrated that the developed HPLC method was sensitive, accurate and selective for the determination of MSL and its metabolite in dog plasma. After orally administering three doses of MSL, it could no longer be detected in dog plasma and its metabolite, salicylic acid, was detected. Salicylic acid showed a single peak in the plasma concentration-time curves and linear pharmacokinetics following the three oral doses (r(2)>0.99). In contrast, only MSL was detected in plasma following intravenous administration. These results will aid in understanding the pharmacological significance of MSL. The developed method was successfully used for evaluation of the oral and intravenous pharmacokinetic profile of MSL in dogs. Copyright (c) 2013 John Wiley & Sons, Ltd.