Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea (Camellia sinensis), has shown cancer preventive activity in animal models. The bioavailability of EGCG in the most commonly used animal species, mice, is poorly understood. Moreover, the pharmacokinetic parameters of EGCG have not been reported previously in mice. Here we report that after administration of EGCG intravenously at 21.8 micro mol/kg or intragastrically at 163.8 micro mol/kg, the peak plasma levels of EGCG in male CF-1 mice were 2.7 +/- 0.7 and 0.28 +/- 0.08 micro mol/L, respectively. EGCG was present mainly (50-90%) as the glucuronide. The plasma bioavailability of EGCG after intragastric administration was higher than previously reported in rats (26.5 +/- 7.5% vs. 1.6 +/- 0.6%). The conjugated EGCG displayed a shorter t(1/2) (82.8-211.5 vs 804.9-1102.3 min) than unconjugated EGCG (P < 0.01, Student's t test). EGCG was present in the unconjugated form in the lung, prostate and other tissues at levels of 0.31-3.56 nmol/g after intravenous administration. Although intragastric administration resulted in lower levels in most tissues compared with intravenous administration (e.g., 0.006 +/- 0.004 vs. 2.66 +/- 1.0 nmol/g in the lung), the levels in the small intestine and colon were high at 45.2 +/- 13.5 and 7.86 +/- 2.4 nmol/g, respectively. This is the first report of the pharmacokinetic parameters of EGCG in mice. Such information provides a basis for understanding the bioavailability of EGCG in mice and should aid in understanding the cancer preventive activity of EGCG.