The cytotoxic activities of methanolic extract and its fractions of Ailanthi Cortex Radicis and column chromatographic eluates of its dichloromethane fraction (DCM fr.) were investigated. DCM fr. Showed the strongest cytotoxicity against hepatoma cells. Furthermore, the active equates 1-3, 8 and 9 were obtained. Effects on free radical generation and the growth of vascular endothelial cells were tested to elucidate the action mechanism of anticancer activity. Eluates 1-3 stimulated free radical generation, while eluates 8 and 9 showed no changes. Especially, eluates 8 and 9 efffectively inhibited the proliferation of vascular endothelial cells in a dose- dependant manner. It is speculated that the anticancer effects of eluates 1-3, 8 and 9 might be due to free radical generation and inhibition of endothelial cell growth, respectively.