The correlations of selenium level and glutathione peroxidase activity in blood and lipid peroxide concentration in plasma from 24 patients of dilated cardiomyopathy were studied. The results showed that in case of dilated cardiomyopathy, the selenium level and glutathione peroxidase activity were significantly lower (P less than 0.05), while lipid peroxide concentration was significantly higher (P less than 0.01) than those of healthy controls. Therefore, it is highly possible that dilated cardiomyopathy is associated with lipoperoxidation damage caused by the deficiency of both selenium and antioxidation ability.