Diabetes mellitus has been known to be a state of increased oxidative stress. Free radical formation and lipid peroxidation are accelerated in this metabolic disorder. Buchu (Allium tuberosum Rottler) contains lots of antioxidative nutrients such as chlorophyll, vitamin C, $eta$-carotene, phenolic compounds and sulfur compounds. To investigate the protective effects of buchu, 10% lyophilized buchu diet was fed to streptozotocin (STZ)-induced diabetic rats for 14 weeks and lipid peroxidation, protein oxidation, contents of reactive oxygen species, activities of antioxidative enzymes and contents of accumulated lipofuscin were measured as indicators of oxidative stress. Hepatic MDA and carbonyl contents tended to decrease in 10% buchu diet group compared with control group. Dietary buchu significantly suppressed lipid and protein oxidation in the skin of rats (p<0.05). Contents of hepatic hydroxyl radicals, which exert the highest toxicity among the reactive oxygen species, were significantly decreased in rats fed 10% buchu diet (P<0.05). Activities of antioxidative enzyme, such as superoxide dismutase, catalase, and glutathione peroxidase, tended to increase in liver and skin of rats fed 10% buchu diet, while hepatic catalase activity was significantly increased in buchu group compared with control group. Buchu supplementation significantly inhibited the accumulation of lipofuscin, an end-product of lipid peroxidation reactions induced by reactive oxygen radicals, in eye tissues compared with control diet (p<0.001). In conclusion, buchu supplementation diminished the oxidative stress, so dietary buchu could help to attenuate diabetes complications.