Abstract: A simple, sensitive and precise capillary GC-ECD method was developed for thedetermination of isosorbide-5-mononitrate in human serum,Pharmacokinetic parameters of the drugwas obtained from the human serum level-time curve measured. Serum samples were extracted with a mixture of ethyl ether-ethyl acetate(4:1), the upperphase was collected and evaporated to about 100μl under a gentle nitrogen stream,Isosorbide dinitratewas used as internal standard.With a human serum sample size of 200μl ,the detection limit of IS-5-MN was found to be about 5 ng/ml,and the athelute recovery from 74%to 85%. The within-dayand between-day relative standard deviation were less than 7%and 9%,respectively. This method was applied to the pharmacokinetic studies of IS-5-MN tablets froth two differentsouroes.Two sets of t_1/2(Ke),T_max and AUC values obtained from 8 volunteers were tested statisti-cally and no significant difference was found.