Although matrine, a primary active component of dried Sophora flavescens root (ku shen), is known to induce apoptosis in a variety of tumor cells in vitro, the molecular mechanism of such apoptosis remains elusive. This analysis of the cell cycle and apoptosis in matrine‐treated human gallbladder carcinoma cells (GBC‐SD) showed that matrine can indeed inhibit cell proliferation and induce G1 cell cycle arrest and apoptosis in a dose‐ and time‐dependent manner. An additional western blot analysis of matrine‐treated cells also showed caspase‐3 and Bcl‐2 activation, as well as cyclinE down‐regulation. Overall, the results indicate that matrine perturbs gallbladder cancer cell progression during the G1 phase by down‐regulating cyclinE and induces apoptosis by decreasing the expression of the antiapoptotic protein Bcl‐2 and increasing expression of the proapoptotic protein Bax. Copyright © 2011 John Wiley & Sons, Ltd.