Blood and plasma viscosity, total blood lipids, triglycerides, total cholesterol, free fatty acids, fibrinogen, hematocrit, and lipidogram were determined in patients with diabetes mellitus type II and coexisting symptoms of the obliterative arteriosclerosis of the lower limbs. Intermittent claudication distance has been measured parallel. The same tests have been carried out after ozone therapy. A significant improvement in the intermittent claudication and reduction in blood and plasma viscosity have been noted. There was statistically significant correlation between intermittent claudication decrease and blood viscosity reduction following ozone therapy.