EtOAc soluble part of MeOH extract of Anemarrhena asphodeloides rhizome was evaluated for the cytotoxicity against the five kinds of human tumor cell lines (A-549, SK-OV-3, SK-MEL-2, XF498 and HCT15) in vitro. Bioassay-guided fractionation of EtOAc soluble part led to the isolation of active compound which was identified as timosaponin A-III showed potent cytotoxic activity, but its genin, sarsasapogenin, did not show cell growth inhibition.