This study was carried out to examine the antioxidant effects of a mixture of mulberry leaves and silkworm powder in plasma and liver of streptozotocin-induced diabetic rats. Sprague-Dawley male rats weighing 100$pm$10 g were used and their diets were supplemented with $0.4\%$ (4 g/kg) of the mixtures. Experimental groups were diabetic rats without supplements (DM group) or with a combination of the supplements: $100\%$ mulberry leaves (M group), $25\%$ silkworm powder mixed with mulberry leaves (25SM group), $50\%$ silkworm powder mixed with mulberry leaves (50SM group), $75\%$ silkworm powder mixed with mulberry leaves (75SM group) or $100\%$ silkworm powder (100S group). The rats were fed experimental diets and water ad libitum. All animals were injected with streptozotocin at the $3^{rd}$ week for inducing diabetes and were sacrificed on $9^{th}$ day thereafter. Hepatic xanthine oxidase (XOD) activity significantly decreased in the mixture supplemented groups compared to the DM group. Hepatic superoxide dismutase (SOD) activity was not significantly different among any of the experimental groups, but glutathione peroxidase (GSH-px) activity increased in the mixture supplemented groups compared to the DM group. In particular, it was the highest in the 50SM group. The hepatic TBARS values were lower in all the mixture supplemented groups than in the DM group, and it was as lowest when ratio of mulberry leaves to silkworm powder was highest. Hepatic lipofuscin contents were similar with the TBARS value. In conclusion, the mixtures containing silkworm powder reduced oxidative damage by strengtbening the antioxidative system and suppressing oxidative stress in the STZ-induced diabetic rat. The 1:1 blend of silkworm powder and mulberry leaves was the most effective combination for antioxidant activity.