The effects of Tuftsin, an immunomodulator agent, in experimental diabetes induced mice was studied. Injecting 40 mg STZ per kg of body weight for 5 consecutive days produced autoimmune diabetes. Treatment with 10 μg/mouse of Tuftsin did not prevent hyperglycemia. On the other hand, 25 μg/mouse of Tuftsin prevented diabetes. These results indicate that high dose Tuftsin seems to be effective in preventing hyperglycemia in diabetic mice and appear to suggest that Tuftsin has an immunomodulatory (suppressive) activity in these animals.