The effects of ethanol-soluble and acidic components (ESAC) from Ganoderma lucidum on tumor growth were investigated in this paper. EASC was prepared by solvent extract method and its components were analyzed by high performance liquid chromatography (HPLC). Effects of ESAC on in vitro growth of 3 cell lines (including human hepatoma BEL 7402,Human cervix uteri tumor-derived HeLa and human umbilical vein endothelial cell line HUVEC) were determined by MTT method. Meanwhile,ESAC was administered to nude mice by peritoneal injection to examine the effects of ESAC on in vivo growth of BEL 7402 hepatoma. In vitro experiments showed IC 50 values of ESAC towards 3 cell lines were 12.4 μg/mL(BEL 7402),129.2 μg/mL(HeLa) and 526.6 μg/mL (HUVEC),respectively. Data from animal tests indicated the tumor inhibition ratios of ESAC were 43.9% (20 mg/kg/d) and 74.9% (5 mg/kg/d) with low toxicity. The results indicated ESAC from G. lucidum had the ability of inhibiting the hepatoma growth selectively,and therefore was a potential product.