Glutathione S-transferase and glutathione peroxidase are a group of multifunctional enzymes that involved in the metabolic conversion of DMBA. When ginseng ether extracts (2 ㎎/㎏, i.p., 10 days) and selenium (5 μmol/㎏, i.p., 10 days) to rats, GST and GSH-px activities showed by 12.3%, 186% as compared with the normal group respectively. Also, this materials inhibited on the formation of DMBA-induced lipoperoxide. Antimutagenic effects of ginseng ether extracts, selenium, and ginseng+selenium in the DMBA (20 ㎍/plate) inducing mutagenicity using Salmonella typhimurium strain TA 98 by the Ames method exhibited by 17%, 22%, and 41%, respectively. Direct additions of ginseng ether extracts (0.5∼2 ㎎/plate) and selenium (1∼4 μmol/plate) with S-9 mixture to the mutagenicity assay system showed 14∼38%, 32∼66% inhibition of DMBA mutagenicity, respectively.