Most patients with dilated cardiomyopathy have a poor prognosis due to progressive and irreversible myocardial dysfunction. Rarely, is a metabolic etiology responsive to specific therapy identified. Although many studies have confirmed that thyroid hormone deficiency is associated with a reversible decrease in myocardial contractility, it has remained controversial whether hypothyroidism alone can cause a dilated cardiomyopathy and clinical heart failure. In this study, we report the case of a patient with severe hypothyroidism and a dilated cardiomyopathy complicated by heart failure, which has receded after recovery to euthyroidism with L-thyroxin therapy. This case suggests that hypothyroidism should be evoked systematically when a dilated cardiomyopathy is diagnosed.