Abstract: Eight ginsenosides (Rb 1,Rb 2,Rb 3,Rd, Rg 3, Rh 1, Rg 1, Re) were analyzed in negative ion scan mode by Electrospray Ion Trap Mass Spectrometer (LCQ) and Triple Quadrupole Mass Spectrometer (API 3000). The pseudomolecular ion ( ) was observed in full scan negative ion ESI mass spectrum of ginsenosides, which was very characteristic to determine the molecular weights of this family of compounds. The glycosidic linkages, the aglycone, and the attached sugar(s) of the ginsenosides could be determined from the collision induced dissociation (CID) spectra of in multi stage full scan mode (ESI MS n ). Moreover, an LC MS n method was established for the analysis of ginsenosides.