Clinical pictures of a patient with progression from hypertrophic cardiomyopathy to dilated cardiomyopathy features in the end stage was described. Echocardiography performed at the age of five years revealed septal hypertrophy without systolic anterior motion (SAM). At 7 years of age, it revealed ventricular septal thickness of 18 mm, left ventricular posterior wall thickness of 24 mm, and marked SAM. Echocardiography at 14 years of age revealed left ventricular dilatation (52 mm in diastole) with poor contraction. Ventricular septal thickness was 18 mm and left ventricular posterior wall thickness was 16 mm. The SAM was no longer present. At autopsy, the heart weighed 590 g, and there was moderate dilatation of the right and left ventricular cavities. Histologically, there were massive fibrosis and myocardial disarray in the right and left ventricular walls.