Abstract: We examined how intake of polyphenols modifies brachial artery flow-mediated dilation (FMD) at rest, and cycling anaerobic performance, in elite athletes. In the first randomized cross-over study, FMD was measured over a three-hour period on two occasions in eight elite male and female athletes after acute consumption of either polyphenols from cranberries and grape seeds (600 mg) or a polyphenol-free placebo drink. Consumption of the polyphenol-rich drink led to a significant increase in FMD compared to placebo (p = 0.02), with a peak at 60 min. In a second study, 12 elite male and female athletes completed a three-kilometer time trial (TT) on an ergocycle on two occasions in random order, either after consumption of 800 mg of polyphenols or a placebo. Acute intake of the polyphenol extract had no impact on the three-kilometer time trial completion. However, plasma lactate levels were significantly lower before and after the TT when subjects consumed the polyphenols vs. placebo (p 0.05). Results suggest that polyphenols from cranberries and grape seeds acutely modifies FMD at rest in elite athletes but this does not translate into enhanced cycling anaerobic performance.