Abstract: A rapid, accurate and sensitive gas chromatographic method was developed for the determination of isosorbide-5-mononitrate(5-ISMN) in 0.5 ml plasma. The instrument was equipped with 5% SE-30 glass packed column (2 m×3 mm) and electron-capture detector. Isosorbide dinitrate (ISDN) was used as internal standard. The plasma was extracted with a mixture of ethyl ether and n-hexane (4∶1) to give mean recoveries of 100.1% of 5-ISMN. The extracts reacted with trifluoroacetic anhydride and the derivatives were analyzed. The calibration curves were linear over a wide range of concentrations (20～800 ng·ml^-1), and the detection limit of 5-ISMN was 2.0 ng·ml^-1. The precisions (RSD%, n=5) of within-day and day-to-day were less than 4% and 6.5%, respectively. The pharmacokinetic characteristics of 5-ISMN in ten human volunteers after a single oral dose of 20 mg 5-ISMN were investigated. The concentration-time curve was fitted to a one-compartment model.