Abstract: Objective: To investigate the inhibitory effects of Genistein on the proliferation of B₁₆ melanoma cells.Methods: B₁₆ melanoma cells were treated with 10,30,90 μmol/L Genistein for 1-4 days.Growth curve test was served as the index to reflect prolifertion activity of B₁₆ melanoma cells,Morphological changes of B₁₆ melanoma cells,melanin content in the supernatant of melanoma cells,distribution of cell cycle were measured by Flow Cytometery.Results: The Genistein at the oncentration of 10,30,90 μmol/L inhibited significantly the growth of B₁₆ melanoma cells in dose dependent manner with statistical significance(P<0.05-P<0.01 vs control).Interestingly,Genistein induced the differentiation of B₁₆ melanoma cells which showed that melanic granule and number of cells decreased.Flow cytometry showed that numerous cells were retarded at S phase of cell cycle.Conclusions: The Genistein at the dose of 10,30,90 μmol/L significantly inhibit the growth of B₁₆cells.