Abstract: Objective: To study the influence of quercetin(QUE) on the growth and apoptosis of human gastric carcinoma cell line BGC-823.Methods: Methyl thiazolyl tetrazolium(MTT) assay was used to determine the influence of different concentrations of QUE on the cell proliferation of BGC-823;the change of cell cycle and apoptosis was observed by flow cytometry(FCM) after the cells were treated with different concentrations of QUE for 24 h;the positive expression rate of Bcl-2 and caspase-3 were detected by immunocytochemical staining.Results: QUE at concentrations ranging from 30 μmol/L to 120 μmol/L significantly inhibited the proliferation of BGC-823 cells in a dose-and-time-dependent manner(P<0.01).FCM analyses showed that QUE arrested BGC-823 cells at the S phase.Expression of Bcl-2 protein decreased following QUE induction in a dose-dependent manner,whereas caspase-3 expression increased significantly compared with that of the control group(P<0.01).Conclusions: QUE can inhibit the growth and induce apoptosis of BGC-823 cells,keeping the cell cycle at S phase.Its mechanisms may be relevant to the down-regulation of Bcl-2 protein expression as well as the up-regulation of caspase-3 expression.