The aim of this study is to clarify the effects of yogurt supplemented with fish oil on plasma lipid and glucose concentrations, and hepatic lipid contents in mice. Male Crlj:CD-1 (ICR) mice were fed five experimental diets for 12 weeks. The experimental diets were as follows: without yogurt and fish oil (control diet); 10% (w/w) yogurt without fish oil [10% FO(-)]; 10% yogurt with fish oil [10% FO(+)]; 30% yogurt without fish oil [30% FO(-)]; 30% yogurt with fish oil [30% FO(+)]. Plasma triacylglycerol concentrations in the 10% FO(+) and 30% FO(-) groups were significantly lower than that in the control diet group (p < 0.05 and p < 0.05, respectively). Plasma total cholesterol and phospholipid concentrations were significantly lower in the 30% FO(+) group than in the control diet group (p < 0.005). Concentrations tended to be lower with supplementation with fish oil. Plasma glucose concentrations in the 10% FO(+) and 30% FO(+) groups were significantly lower than those in the control diet group (p < 0.005 and p < 0.01, respectively). Hepatic triacylglycerol and total cholesterol contents in the 30% FO(+) group were significantly lower than those in the control diet group (p < 0.05 and p < 0.005, respectively). These results suggest that plasma triacylglycerol and glucose concentrations are effectively decreased by supplementation of yogurt with fish oil.