Two siblings presented with symptoms of left ventricular dysfunction and ventricular arrhythmias. Echocardiography and left ventriculography revealed dilatation, diffuse hypokinesis and apical aneurysm of the left ventricle in both cases. Myocardial infarction was unlikely by history and examinations. We diagnosed them as cases of familial dilated cardiomyopathy complicated by left ventricular aneurysm.