The cardiac features of hyperthyroidism are well known and are given due consideration in most works on heart disease. On the other hand, the myocardial weakness and heart failure nearly always found associated with hypothyroidism and myxedema are apparently little appreciated by the profession and are given scant consideration in works on heart disease. My first presentation of a typical case of myxedema heart at staff roundsat the Minneapolis General Hospital was received with great skepticism. Osler,1in the chapter on myxedema, says, "The functions of the heart are normal." Hirschfelder2says: "In myxedema there are symptoms of cardiac weakness. The patients get out of breath on very slight exertion. The pulse is small and weak.... However, as Kraus points out, the cardiac features in cachexia thyreopriva are not prominent features of the disease and hence are of little importance in connection with diseases of the heart." Mackenzie