Abstract: Abstract　Objective: To investigate the inhibitory effects and possible mechanisms of matrine injections on the proliferation and apoptosis of human gastric cancer cell line MGC803. Methods: After matrine injections, cell proliferation was determined by the MTT assay. Cell morphology and apoptosis quantity were examined by the terminal deoxynucleotidyl transferase dUTP nick end labeling ( TUNEL ) assay. The expression levels of Bcl-2, Bax, and Caspase-3 proteins were observed by Western blot analysis. Results: Matrine injections significantly inhibited the proliferation of MGC803 cells in concentration- and time-dependent manners ( P < 0.001). The number of apoptotic cells in the matrine-treated group was greater than that of the control group ( P < 0.05 ). The expression level of Bcl-2 was down-regulated by matrine. With increased matrine concentration, the ratio of Bcl-2 to Bax  decreased, consequently accelerating procaspase-3 activation ( P < 0.05 ). Conclusion: Matrine injections inhibited the growth of MGC803 cells in concentration- and time-dependent manners by inducing apoptosis. This action may be mediated by the down-regulation of Bcl-2/Bax, resulting in Caspase-3 activation.