Objective:To establish a sensitive and specific LC/MS/MS method for the determination of granisetron in human plasma,and to apply it in investigating the pharmacokinetics of granisetron hydrocloride capsule in healthy volunteers.Methods: Twelve healthy male volunteers were given single oral dose of 2 mg granisetron hydrocloride capsules.The plasma concentrations of granisetron were determined by LC/MS/MS method after liquid-liquid extraction.The pharmacokinetic parameters were calculated by noncompartment model.Results: The calibration curve was linear within a concentration range of 0.501-20.04 ng/ml,with the limit of quantification being 0.501 ng/ml.The main pharmacokinetic parameters of granisetron in the volunteers were as following: Cmax(6.93±1.90) ng/ml,tmax(1.35±0.29) h,t1/2(5.59±1.87) h,MRT (8.05±1.84) h,Cl/F(54.23±16.08) L/h,AUC0-24 (36.61± 8.87) ng·h·ml-1 and AUC0-∞ (39.32±9.36) ng·h·ml-1.Conclusion: The present method is accurate,sensitive and reproducible for the determination of granisetron levels in human plasma.It is suitable for pharmacokinetic study of granisetron hydrochloride capsule in human.