AIM: To study the blocking effects of genistein on cell proliferation cycle in human gastric carcinoma cells (SGC-7901) and the possible mechanism. METHODS: MTT assay was applied in the detection of the inhibitory effects of genistein on cell proliferation. Flow cytometry was used to analyze the cell cycle distribution. Immunocytochemical technique and Western blotting were performed to detect the protein expression of cyclin D_1, cyclin B_1 and p21~(waf1/cip1). RESULTS: Genistein significantly inhibited the growth and proliferation of human gastric carcinoma cells (SGC-7901). Seven days after treatment with different concentrations of genistein (2.5, 5.0, 10.0, 20.0 μg/mL), the growth inhibitory rates were 11.2%, 28.8%, 55.3%, 84.7% respectively and cell cycles were arrested at the G(2)/ M phase. Genistein decreased cyclin D_1 protein expression and enhanced cyclin B_1 and p21~(waf1/cip1) protein expression in a concentration-dependent manner. CONCLUSION: The growth and proliferation of SGC-7901 cells can be inhibited by genistein via blocking the cell cycle, with reduced expression of cyclin D_1 and enhanced expression of cyclin B_1 and p21~(waf1/cip1) protein in the concentration range of 0-20 μg/mL. AIM: To study the blocking effects of genistein on cell proliferation cycle in human gastric carcinoma cells (SGC-7901) and the possible mechanism. METHODS: MTT assay was applied in the detection of the inhibitory effects of genistein on cell proliferation. Flow cytometry was used to analyze the cell cycle distribution. Immunocytochemical technique and Western blotting were performed to detect the protein expression of cyclin D_1, cyclin B_1 and p21 waf1 / cip1. RESULTS: Genistein significantly inhibited the growth and proliferation of human gastric carcinoma cells ( SGC-7901). Seven days after treatment with different concentrations of genistein (2.5, 5.0, 10.0, 20.0 μg / mL), the growth inhibitory rates were 11.2%, 28.8%, 55.3%, 84.7% respectively The G (2) / M phase. Genistein reduced cyclin D_1 protein expression and enhanced cyclin B_1 and p21 ~ (waf1 / cip1) protein expression in a concentration-dependent manner. CONCLUSION: The growth and proliferation of SGC-7901 cells can be inhibited by genistein via blocking the cell cycle, with reduced expression of cyclin D_1 and enhanced expression of cyclin B_1 and p21 ~ (waf1 / cip1) protein in the concentration range of 0-20 μg / mL.