Vascular NADPH oxidase plays a pivotal role in producing superoxide in endothelial cells and thus acts in the initiation and development of inflammatory cardiovascular diseases such as atherosclerosis. Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, has multiple beneficial effects for treating cardiovascular disease but the effect of EGCG on the expression of vascular NADPH oxidase remains unknown. In this study, we investigated the mechanism(s) by which EGCG might inhibit the expression of subunits of NADPH oxidase, namely p47phox, p67phox and p22phox, induced by angiotensin II (Ang II) in human umbilical vein endothelial cells. Ang II increased the expression levels of p47phox, p67phox, and p22phox, but EGCG counteracted this effect on p47phox. Moreover, EGCG did not affect the production of reactive oxygen species induced by Ang II. These data suggest a novel mechanism whereby EGCG might provide direct vascular benefits for treating inflammatory cardiovascular diseases.