A new, sensitive LC/MS/MS method was developed for the quantification of ruscogenin and neoruscogenin in hydrolyzed extracts from Ruscus aculeatus L. (Liliaceae). The two sapogenins were separated on a Zorbax SB-C18 column under isocratic conditions. The detection was performed in the multiple reaction monitoring mode using an ion trap mass spectrometer with an electrospray ionization source operated in positive ionization mode. For the quantification of the ruscogenin and neoruscogenin, calibration curves were constructed over the range of 2-1000 ng/mL. This is the first reported LC/MS/MS method for the simultaneous analysis of ruscogenin and neoruscogenin, and it showed superior sensitivity when compared with other assays described in the literature. The method has been successfully applied to quantify the two sapogenins in aerial (phylloclades) and underground parts (rhizomes, roots) of Ruscus aculeatus L.