The aim of this study was to investigate the effect of naringin on the bioavailability and pharmacokinetics of paclitaxel after oral administration of paclitaxel or its prodrug coadministered with naringin to rats. Paclitaxel (40 mg/kg) and prodrug (280, 40 mg/kg paclitaxel equivalent) were coadministered orally to rats with naringin (1, 3, 10 and 20 mg/kg). The plasma concentrations of paclitaxel coadministered with naringin increased significantly (p<0.01 at paclitaxel, p<0.05 at prodrug) compared to the control. The areas under the plasma concentration-time curve (AUC) and the peak concentrations (C(max)) of paclitaxel with naringin significantly higher (p<0.01) than the control. The half-life (t(1/2)) was significantly (p<0.05) longer than the control. The absolute bioavailability (AB, %) of paclitaxel with naringin was significantly higher (3.5-6.8%, p<0.01) than the control (2.2%). Absorption rate constant (K(a)) of paclitaxel with naringin increased, but not significantly. The AUC of paclitaxel after coadministration of prodrug with naringin to rats was significantly (p<0.05) higher than the prodrug control. The relative bioavailability (RB, %) of paclitaxel after coadministration of prodrug with naringin was 1.35-1.69-fold higher than prodrug control. The absolute bioavailability (AB, %) of paclitaxel after coadministration of prodrug with naringin increased significantly (p<0.05) from 6.6 to 9.0% and 11.2%. The bioavailability of paclitaxel coadministered as a prodrug with or without naringin was remarkably higher than the control. Paclitaxel prodrug, a water-soluble compound concerning with its physicochemical properties, passes through the gastrointestinal mucosa more easily than paclitaxel without obstruction of P-gp and cytochrome P-450 in the gastrointestinal mucosa. Oral paclitaxel preparations which is more convenient than the IV dosage forms could be developed with a prodrug form with naringin.