Objective To study the influence of wheat germ agglutinin (WGA) on cell growth and expressions of apoptosis genes in MDA-MB-231 cells. Methods MDA-MB-231 cells were cultured in DMEM containing 10% fetal bovine serum at 37℃ in a humidified atmosphere with 5% COSUB>2/SUB>.The experiment was performed on five groups: WGA groups were given 0.035, 0.07,0.14,0.28μmol/L WGA respectively, while in the control group the cells were merely grown in DMEM medium solution. Acid phosphatase assay(APA),flow cytometry（FCM） and Western blotting were used to detect the changes of cell viability,apoptosis ratio,mitochondrial transmembrane potential, the expressions of apoptosis-related protein poly ADP-ribose polymerase(PARP) and cytochrome C. Each experiment was done four times independently. Results Cell growth was inhibited after MDA-MB-231 cells were co-cultured with different concentrations of WGA for 24, 48, and 72 hours. Compared with human breast epithelia cells line HBL-100, MDA-MB-231 cells were more sensitive to WGA. After cells were treated with WGA for 24 hours, cell numbers reduced, volumes diminished.Early apoptosis ratio caused by WGA(0.14μmol/L, 0.28μmol/L,24 hours) were ( 28.7±3.48)% and ( 30.15±3.96)%, while the late apoptosis rates were ( 53.66±4.21)% and ( 63.18±5.53)%. Mean fluorescence intensity (MFI) of mitochondrial transmembrane potentials in MDA-MB-231 cells decreased.Apoptosis-related protein PARP showed an cleavage and cytochrome C expression increased in a dose-depandance manner. Conclusion WGA could significally restrain cell growth of breast cancer cell line