It is agreed that many of the antitumor effects of (-)-epigallocatechin gallate (EGCG) are mediated by various other effects. We report a new finding, namely, the antiproliferation potential and mechanism of methylated-(3'')-epigallocatechin gallate analog (MethylEGCG) having a stronger anti-oxidation effect than EGCG. MethylEGCG inhibited activity of vascular endothelial growth factor (VEGF)-depended VEGF receptor 2 and p42/44 MAPK, cell proliferation, and tube formation in human umbilical vascular endothelial cells (HUVECs) at 1 μ M. Even low- dose (1.1 mg/kg i.p. 8.3 mg/kg p.o.) administration suppressed tumor growth in xenografted Huh7 hepatoma mice by 50%. CD31 positive cells, visualized in blood vessels, were reduced in tumors by 18%, suggesting high antitumor activity via inhibition of angiogenesis. This study indicated that the modification of the 3'' position methylation of EGCG (MethylEGCG) could reduce cell growth effects at a low concentration in vivo.