The purpose of this study was to investigate the effect of paclitaxel in combination with 20 (s)-ginsenoside Rg3 on its anti-tumour effect in nude mice.In the Caco-2 transport assay, the apparent permeability from the apical side to the basal side (Papp) (A-B) and Papp (B-A) of paclitaxel were measured when co-incubated with different concentrations of 20 (s)-ginsenoside Rg3.The results indicated that the penetration ofpaclitaxel through the Caco-2 monolayer from the apical side to the basal side was facilitated by 20 (s)-ginsen0side Rg3 in a concentration-dependent manner.Meanwhile, 20 (s)-ginsenoside Rg3 inhibited P-gtycoprotein (P-gp), and the maximum inhibition was achieved at 80 mM (P<0.05).The pharmacokinetic parameters ofpaclitaxel after oral co-administration of paclitaxel (40mg/kg) with various doses of 20 (s)-ginsenoside Rg3 in rats were investigated by an in vivo pharmacokinetic experiment.