Abstract: Objective: To investigate the role of grape seed extract(GSE) in inhibiting the growth of human breast cancer cells.Methods: MTT assay was employed to determine the inhibitory effect of GSE on human breast cancer cells,and suitable experimental concentration of GSE was screened.The influence of GSE on the generation of reactive oxygen species(ROS) in breast cancer cells was evaluated by flow cytometry;semiquantitative RT-PCR was used to detect the expression level of Bcl-2 gene and Bax gene related to tumor apoptosis.Results: GSE inhibited the growth of breast cancer cells in a dose-dependent manner(P<0.01),and the proper dosage of IC₅₀ was 100 μg/ml.GSE might reduce the generation of ROS as well as the expression of Bcl-2 gene in tumor cells,but had no influence on the expression of Bax gene,and the value of Bcl-2/Bax decreased significantly(P<0.01).Conclusions: GSE can inhibit the growth of human breast cancer cells,which might be achieved by reducing the generation level of ROS and regulating the expression of Bcl-2 gene and Bax gene.