The purpose of this research has been to assess the role of lipidic peroxides, the involvement of the superoxide radical and of sulfhydrylic groups in isoproterenol-induced myocardium hypertrophy in rats. The results of our investigations point to increased values by 25% of plasma lipidic peroxides and in the myocardium and to a decrease of sulfhydrylic groups and of superoxide dismutase in the groups with myocardial hypertrophy, 15% and 10% respectively, compared to the controls. The comparative analysis of the data enabled us to infer the consequences of lipidic peroxides and of free radicals presence in excess and to assess the protector role of fosfobion- an energising compound-against the structural lesions of the myocyte.