Quercetin is one of the bioflavonoid compounds and has multiple biological effects such as antioxidant and effective anti-inflammatory agent. Melanin has an important role in protecting human skin from the damaging effects of ultra-violet W) radiation. We studied the effect of quercetin on proliferation of B16/F10 melanoma cells. After 48h treatment of cells with quercetin, the cells exhibited a dose-dependent inhibition in their proliferation without apoptosis. Therefore, the decrease in cell numbers may be due to cell growth arrest, not due to cell death by cytotoxicity. We also investigated the effect of quercetin on melanogenesis of this cells. B16/F10 melanoma cells were grown for 48h in the presence of 0.01~50$mu extrm{g}$/ml quercetin and the total melanin contents were measured. Quercetin stimulated melanization of the cells in low concentrations (0.01~20$mu extrm{g}$/ml), whereas it inhibited melanization in high concentrations (30~50$mu extrm{g}$/ml). It was observed that quercetin differently regulates melanogenesis of B16/F10 melanoma cells dependent on its concentrations.