Protective effect of skin by antioxidative dietary buchu (Chinese chives, Allium tuberosum Router), was evaluated in ICR mice fed diets containing 2% or 5% buchu for 12 months. Lipid peroxidation and protein oxidation in skin, with or without ultraviolet B (UVB) irradiation, activities of antioxidative enzymes, total glutathione concentrations, and non-soluble collagen contents were measured. Dietary buchu decreased significantly in TBARS and protein carbonyl levels in skin compared to the control group, and were lower in those fed 5% than 2% buchu diet group. ICR mice exhibited an age-dependent decrease in antioxidative enzyme activities and total glutathione concentrations on the control diet, but in the groups fed buchu diet the enzyme activities and glu-tathione concentrations remained at youthful levels for most of the study. SOD, glutathione peroxidase, and catalase activities as well as total glutathione concentrations increased with time in the skins of the mice fed buchu diets. Lipid peroxidation and protein oxidation provoked by UVB irradiation on ICR mice skin homogenates were also significantly inhibited by dietary buchu. The buchu diets also decreased the formation of non-soluble collagen in mice skin, compared to the control group. These results suggest that antioxidative components and sulfur-compounds in buchu may confer protective effect against oxidative stress resulting from aging and exposure to ultraviolet irradiation.