Introduction: Epidemiological studies have shown a putative correlation between the moderate consumption of red wine and a lowered risk of coronary heart disease (1). Biological mechanisms proposed for red wine-derived phenolic compounds include estrogenic activity, antioxidant activity, inhibition of platelet aggregation, modulation of lipid metabolism, and proliferation of smooth muscle cells(2, 3). Resveratrol (RVT), a stilbene polyphenol found in grapes and red wine, exhibits vasorelaxing effects, mainly via a NO-dependent mechanism. Nitric oxide is an important mediator for the relaxation of corpus cavernosal muscle which is the fundemental event in erection. Thus, this study was designed to investigate the effect of RVT on phenylephrine-induced contractile response of the rat corpus cavernosum strips. Materials and methods: Corpus cavernosum strips were suspended in oxygenated Krebs buffer at 37C. Isometric contractions were recorded using a force-displacement transducer coupled to a polygraph. The strips were placed under a resting tension of 1 g and after a 60-min of equilibration, the contractile response to phenylephrine (10-5M) followed by relaxation responses to cumulative addition of RVT (10-10-10-4 M) was recorded. Then, the responses of the strips to RVT were repeated in the presence of a non-selective NOS inhibitor L-NAME (10-5M). Results: The phenylephrine-precontracted corpus cavernosum strips showed relaxation in a dose-dependent fashion by RVT added cumulatively. The responses of the strips to RVT showed a significant reduction at all concentrations of RVT in the presence of L-NAME (p<0.05-0.001). Conclusions: The results of the study suggest that RVT causes relaxation of isolated rat corpus cavernosum strips by a mechanisms involving NO.