This study was carried out to investigate the effects of rice germ oil supplement on the lipid metabolism of insulin-dependent diabetic mice. Streptozotocin-induced diabetic mice were fed three kinds of experimental diets with 20% lipid, composed of 20% lard (L) : 10% lard and 10% rice germ oil (LRGO) ; and 20% rice germ oil (RBO), respectively, for 7 weeks. Diet intake, body weight, organ weight and lipid levels of serum, liver and feces were measured. There was no significant difference in diet intake, body weight and organ weight among the experimental groups. But the concentrations of serum triglyceride in the LRGO and RGO groups, and of serum total cholesterol in the RGO group, were significantly lower than those of the L group fed the 20% lard diet. The levels of hepatic total lipid of the RGO group, and of hepatic total cholesterol of the LRGO and RGO groups were significantly lower than those of the L group. The contents of total lipid and total cholesterol excreted in the feces of the LRGO and RGO groups were higher than those of the L group. These results suggest that rice germ oil can reduce the levels of total cholesterol concentrations in the serum or livers of insulin-dependent diabetic mice, and that the hypolipidemic effect of rice germ oil may be due to increasing fecal lipid excretion and decreasing lipid absorptivity.