The purpose of this study was to investigate the effects of vitamin E on microsomal mixed function oxidase system of kidney in streptozotocin(STZ) induced diabetic rats. Sprague-Dawley male rats weighing 140$pm$10g were randomly assigned to one control and three STZ-diabetic groups which were subdivided into vitamin E free diet(DM-0E group) 40mg vitamin E per kg diet(DM-40E group) and 400mg vitamin E per kg diet(DM-400E group). Vitamin E level of normal group was 40 mg per kg diet. Diabetes was experimentally induced by intravenous administration of 55 mg/kg B.W of STZ in citrate buffer(pH4.3) after 4 weeks feeding of experimental diets. Animals were sacrificed at the 6th day of diabetic state. The contents of cytochrome P450 in kidney were increased by 82, 54, 41% in DM-0E, DM-40E and DM-400E groups respectively when compared with normal group. The contents of cytochrome b5 in kidney were increased by 28% in DM-0E when compared with normal group but those of DM-40E and DM-400E groups were similar to that of normal group. The activities of NADPH-cytochrome P450 reductase in kidney that were increased by 35% in DM-0E group. Levels of TBARS(thiobarbituric acid reactive substance) in kidney were increased by 207, 129% and 72% in DM-0E and DM-400E groups respectively when compared with normal group but those of DM-40E and DM-400E groups were 26,44% lower than that of DM-0E groups. It is know that the activities of MFO system and lipid peroxidation were inhibited in kidney of STZ-induced diabetic rat by administeration of high doses of vitamin E.(Korean J Nutrition 33(6) : 619~624, 2000)