Trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene), a naturalpolyphenol, displays diversified bioactivities that are crucial in chemoprevention of cancer and cardiovascular diseases. Equally promising action is exerted by resveratrol analogues, mainly pterostilbene (3,5-dimethoxy-4'-hydroxy-trans-stilbene) and piceatannol (3,5,3', 4'-tetrahydroxy-trans-stilbene). Although fruits and their products are the main natural source of resveratrol and their analogues, recently these polyphenols have been commercially available in numerous pharmaceutical preparations and diet supplements. The aim of this review is to present the status of clinical studies on chemopreventive/chemotherapeutic effect of resveratrol and its analogues.