Resveratrol, is a phytoalexin present in a wide variety of plant species, including mulberries, peanuts and grapes, and thus is a constituent of the human diet. It exists in two isoforms; cis-resveratrol and trans-resveratrol, where the trans-isomer is the more stable form. While trans to cis isomerisation is facilitated by ultraviolet light and high pH, the cis to trans conversion is facilitated by visible light, high temperature, or low pH. Resveratrol has been the focus of numerous in vitro and in vivo studies investigating its biological attributes, which include antioxidant and anti-inflammatory activities, anti-platelet aggregation effect, anti-atherogenic property, estrogen-like growth promoting effect, growth inhibiting activity, immunomodulation, and chemoprevention (1-3). In fact, recently, it has been demonstrated that the stilbene blocks the multistep process of carcinogenesis at various stages: tumor initiation, promotion, and progression. More recent data provide interesting insights into the effect of this compound on the lifespan of yeast and flies, implicating the potential of resveratrol as an anti-aging agent in treating age-related human diseases (1). Over the last few years, a number of studies have provided evidence of an important role of reactive oxygen species (ROS) or reactive oxygen metabolites (ROM) in mediating the development of oxidative stress. Excessive ROS accumulation may induce the oxidative modification of cellular macromolecules (lipid, proteins and nucleic acids) with deleterious potential. Evidence has accumulated that resveratrol is both a free radical scavenger and a potent antioxidant because of its ability to promote the activities of a variety of antioxidative enzymes. The ability of the polyphenolic compounds to act as antioxidants depends on the redox properties of their phenolic hydroxyl groups and the potential for electron delocalization across the chemical structure. Nevertheless, depending on the concentration of the phytoalexin and the cell type, it has also been shown that resveratrol can exhibit prooxidant properties, leading to oxidative breakage of cellular DNA in the presence of transition metal ions such as copper. Recently it has been proposed that such prooxidant action could be a common mechanism for anticancer and chemopreventive properties of plant polyphenols (4,5). This paper is intended to provide the reader an up-date of the antioxidant and prooxidant properties of resveratrol and its clinical implications.