Resveratrol (3,5,4'-trihydroxystilbene), a natural product derived from grapes, has been reported to exert a plethora of biological functions. Recent studies suggest that resveratrol could act as a cardioprotective agent by controlling the oxidation of low density lipoproteins, as well as the proliferation of endothelial cells. Since migration and proliferation of smooth muscle cells (SMCs) in the intima of susceptible vessels is also widely accepted as a requisite for atherogenesis, we investigated the effects of resveratrol on proliferation and cell cycle control of cultured smooth muscle cells. Results of these experiments are reported herein. Resveratrol reduces SMC proliferation in a dose-dependent manner, with 50-100 microM resveratrol resulting in 70-90% reduction of SMC proliferation induced by such diverse mitogens as serum, endothelin and PDGF. The anti-mitogenic effects of resveratrol are not mediated by the induction of apoptosis, but appear to relate to a G1-->S block in cell cycle traverse. These results give further support to the hypothesis that resveratrol holds promise as an anti-atherosclerotic agent.