Following ginsenoside-Rb1-hydrolyzing assay, strictly anaerobic bacteria were isolated from human feces and identified as Prevotella oris. The bacteria hydrolyzed ginsenoside Rb1 and Rd to $20-O-{eta}-D-glucopyranosyl-20(S)-protopanaxadiol$ (I), ginsenoside Rb2 to $20-O-[{alpha}-L-arabinofuranosyl (1{ ightarrow}6)-{eta}-D-glucopyranosyl] - 20(S)-protopanaxadiol$ (ll) and ginsenoside Rc to $20-O-[{alpha}-L-arabinofuranosyl (1{ ightarrow} 6){eta}-D-g1ucopyranosyl]-20(S)-protopanaxadiol$ (III) like fecal microflora, but did not attack ginsenoside Re nor Rgl (Protopanaxatriol-type). Pharmacokinetic studies of ginseng saponins was also performed using specific pathogen free rats and demonstrated that the intestinal bacterial metabolites I-111, 20(S)- protopanaxatriol(IV) and 20(S)-protopanaxadiol(V) were absorbed from the intestines to $blood(0.4-5.1;{mu}g/ml)$ after oral administration with total saponin(1 g/kg/day).