BACKGROUND&AIM: The anti_tumor active components were isolated from Acanthopanax gracilistylus to identify it's molecular weight and supply the scientific evidence for developing new anti_tumor drugs. MATRAIAL AND METHODS: The effects of the active component on the proliferation of tumor cells was investigated by 3 H_TdR inˉcorporation methods.The active component was isolated2D by chromatography.Its elements and molecular weight were measured By SDS_PAGE and2D electrophoresis.Its chemical nature was analyz...