MTT assay, annexin v assay, flow cytometry, caspase-3 assay and Real-time PCR were used to evaluate apoptosis in breast cancer cells.<h4>Results</h4>The expression rate of apoptotic genes caspase-3, caspase-8, caspase-9, the ratio of BAX /Bcl-2 as well as the expression of P53, BRCA1, GADD45 genes were increased significantly after treatment of T47D breast cancer cells with myricetin. The gene discussed is CASP9; the disease is breast cancer.