Endomyocardial fibrosis is an uncommon disease in Spain, with the most frequent clinical feature being congestive heart failure syndrome. Complete atrioventricular block is exceptional. Two-dimensional echocardiography is a fundamental investigation achieving the diagnosis. Surgical treatment is recommended in symptomatic patients. We present a patient with heart failure secondary to endomyocardial fibrosis with complete atrioventricular block and an infrequent echocardiographic image of a polycystic mass in the free right ventricular wall.