By using red wine (RW), dealcoholized red wine (DARW), polyphenols-stripped red wine (PSRW), ethanol-water solution (ET), and water (W), the role of wine polyphenols, ethanol, and urate on vascular function was examined in humans (n=9 per beverage) and on isolated rat aortic rings (n=9). Healthy males randomly consumed each beverage in a cross-over design. Plasma ethanol, catechin, and urate concentrations were measured before and 30, 60 and 120 minutes after beverage intake. Endothelial function was assessed before and 60 minutes after beverage consumption by normalized flow-mediated dilation (FMD). RW and DARW induced similar vasodilatation in the isolated vessels whereas PSRW, ET, and W did not. All ethanol-containing beverages induced similar basal vasodilatation of brachial artery. Only intake of RW resulted in enhancement of endothelial response, despite similar plasma catechin concentration after DARW. The borderline effect of RW on FMD (P=0.0531) became significant after FMD normalization (P=0.0043) that neutralized blunting effect of ethanol-induced basal vasodilatation. Effects of PSRW and ET did not differ although plasma urate increased after PSRW and not after ET, indicating lack of urate influence on endothelial response. Acute vascular effects of RW, mediated by polyphenols, cannot be predicted by plasma catechin concentration only.