Patients with cardiac infarction show a decrease in glutathione peroxidase and superoxide dismutase activities, which are beginners in the scavenger processes of lipid peroxide and superoxide radicals, respectively. In this study, we investigate the effects of endovenous ozone therapy on serum lipid pattern and on antioxidant defense system, such as te glutathione redox one, in the blood of patients with myocardial infarct. Twenty-two patients who had an infarction, between 3 months and 1 year before the study, were treated with ozone by autohemotherapy during 15 sessions. A statistically significant decrease in plasma total cholesterol and low density lipoprotein was observed. High biologically significant increases on erythrocyte glutathione peroxidase and glucose 6-phosphate dehydrogenase activities were found. There was no change in plasma lipid peroxidation level. It was concluded that endovenous ozone therapy in patients with myocardial infarction has a beneficial effect on blood lipid metabolism, provoking the activation of antioxidant protection system.