Based on the antioxidant activity of panaxytriol, its effect on glutathione peroxidase activity, ornithine decarboxylase induction in mouse epidermis and 3-methylcholanthrene (MCA)induced skin tumorigenesis were investigated. The effect of panaxytriol on croton oil-induced edema of mouse ears was also investigated. As results, panaxytriol significantly prevented decrease in gluthathione peroxidase activity and ornithine decarboxylase induction caused by croton oil. In addition, panaxytriol significantly inhibited croton oil-induced edema. In BALB/c mice receiving MCA, panaxytriol afforded protection by delaying the subsequent development of skin tumors. It is suggested that panaxytriol have potential for modifying the risk of skin tumorigenecity, which may be supported in part by protection from free radical-induced reactions.