In many endocrine diseases we can find a heart disorder. We present a case of a young patient aged 34 years, who was examined for non-specific ST-T abnormalities on ECG and a new-diagnosed left ventricle dysfunction with suspicion to the acute coronary syndroma. However, this diagnosis wasn't verified. Endocrinological examination detected the Addison's disease and a severe hypothyreosis. After the hormonal substitution therapy was given, the patient became asymptomatic and the ECG- and echocardiographic changes disappeared.