Vascular endothelial cells (EC)1 are an important target of estrogen action through both the classical genomic, i.e., nuclear-initiated, activities of estrogen receptors alpha and beta (ERalpha and ERbeta) and the rapid "non-genomic", i.e., membrane-initiated, activation of ER that stimulates intracellular phosphorylation pathways. We tested the hypothesis that the red wine polyphenol trans-resveratrol activates MAPK signaling via rapid ER activation in bovine aortic EC (BAEC), human umbilical vein EC (HUVEC), and human microvascular EC (HMEC). We report that BAEC, HUVEC, and HMEC express ERalpha and ERbeta. We demonstrate that resveratrol and estradiol (E2) rapidly activated MAPK in a MEK-1, Src, matrix metalloproteinase (MMP), and epidermal growth factor-receptor (EGF-R) -dependent manner. Importantly, resveratrol activated MAPK and endothelial nitric oxide synthase (eNOS) at nM concentrations, i.e., an order of magnitude less than that required for ER genomic activity, and concentrations possibly achieved transiently in serum following oral red wine consumption. Co-treatment with ER antagonists ICI 182,780 or 4-hydroxytamoxifen (4-OHT) blocked resveratrol- or E2- induced MAPK and eNOS activation, indicating ER-dependence. We demonstrate for the first time that ERalpha- and ERbeta- selective agonists propylpyrazole triol (PPT) and diarylpropionitrile (DPN), respectively, stimulate MAPK and eNOS activity. A red, but not a white, wine extract also activated MAPK and activity was directly correlated with the resveratrol concentration. These data suggest that ER may play a role in the rapid effects of resveratrol in EC and that some of the atheroprotective effects of resveratrol may be mediated through rapid activation of ER signaling in EC.