SummaryFrom the study of an unselected material of 111 patients with hyperthyroidism—in 31 % associated with thyrocardiac disease—and from extensive search of the literature, the authors reviewed some particular aspects of«cardiothyreosis». The incidence of thyrocardiac disease appeared to be related with increasing age (as already known from other studies) whereas the thyrotoxic cardiopathy was of greater severity in the cases with preexisting heart disease (present in 1/3 of the patients). There was a trend (although a not statistically significant one) towards an increase of the frequency of heart disease in the patients with recurrent hyperthyroidism. The preferential association of thyrocardiac disease with toxic adenoma, often referred to in the literature, could not be confirmed. Cardiomegaly and atrial fibrillation both occurred either as an isolated phenomenon or in combination with cardiac failure.For the treatment of the«cardiothyreotic»patient the authors prefer the association of radioiodine and antithyroid agents.