Anti-allergic effect of 20(S)-protopanaxatriol (PPT), an intestinal metabolite of ginseng saponins was investigated in the guinea pig lung mast cells (GPMCs) and mouse bone marrow-derived mast cells (BMMCs) activated by specific antigen/antibody reaction. Methods: Increasing concentrations of PPT were pretreated 5 min before antigen stimulation, and various inflammatory mediator releases and their relevant cellular signaling events were measured in those cells.