A sensitive method for quantification of pinaverium bromide in human plasma was established using liquid chromatography-electrospray ionization tandem mass spectrometrv(LC-ESI-MS/MS). Glimepiride was used as internal standard. Pinaverium bromide and internal standard in plasma sample were extracted using tert-but}lmethvlether(TBME). A centrifuged upper laver was then evaporated and reconstituted with mobile phase of acetonitrile-5 m1VI ammonium formate (8020. pH 3.0). The reconstituted samples were injected into a C_(18) reversed-phase column. Using MS/MS with multiple reaction monitoring (MRM) mode. pinaverium and glimepirde were detected without severe interference from human plasma matrix. Pinaverium produced a protonated precursor ion ([M+H]^(+)) at m/z 510.3 and a corresponding product ion at m/z 228.9. Internal standard produced a protonated precursor ion ([M+H] ^(+)) at m/z 491.5 and a corresponding product ion at m/z 352.0. Detection of pinaverium bromide in human plasma was accurate and precise. with limit of quantitation at 0.5 ng/ml. The method has been successfully applied to bioavailability study of pinaverium bromide tablet in Korean healthy male volunteers. Pharmacokinetic parameters such as AUCr. C_(max) T_(max). K_(el) and t_(l/2) were calculated.