An extract of heat-processed Achyranthes fauriei roots showed more potent cytotoxic activity against human hepatoma SK-Hep-1 cells than that of the crude plant. Employing a bioassay-linked HPLC-ELSD (high performance liquid chromatography-evaporative light scattering detector) method, followed by silica gel column chromatography, a cytotoxic triterpenoid saponin, chikusetsusaponin IVa was isolated. It is contributive to the increased cytotoxic activity of the heat-processed. The amount of chikusetsusaponin IVa from the roots of Achyranthes fauriei was significantly increased after heat-processing.