Piceatannol (trans-3,3',4,5'-tetrahydroxy-stilbene) is a natural stilbene occurring in a number of plant species, and it has been shown to have beneficial effects on human health. The compound can seldom be consumed by humans, because it occurs in non-food plants, or in non-edible organs. Here we show for the first time that grapes (Vitis vinifera L. cv. Cabernet Sauvignon) have significant amounts of piceatannol (0.052 µg g-1 fresh wt). The identity of piceatannol was confirmed by HPLC and LC-MS.