BACKGROUND Familial dilated cardiomyopathy (FDCM) is characterized by clinical and genetic heterogeneity. There are still few survival studies concerning this subgroup of patients. OBJECTIVE To determine the prognosis of patients with FDCM on optimal medical therapy and attending a heart failure clinic. METHODS This is a prospective study including patients with FDCM, defined according to the guidelines of the European Society of Cardiology. Cardiovascular morbidity and all-cause mortality were evaluated. RESULTS Thirty-six patients, 23 (64%) men, were followed for 3.8 +/- 2.5 years. Age at baseline was 42 +/- 14 years and 67% were in NYHA class II. In 22% heart failure symptoms first occurred after a respiratory infection, and in 6%, after pregnancy/delivery. Most patients were in sinus rhythm (89%) and 33% had left bundle branch block (LBBB). Baseline left ventricular (LV) ejection fraction was 28 +/- 9%, LV end-diastolic diameter was 68 +/- 8 mm and left atrial dimension was 46 +/- 9 mm. Baseline serum sodium was 140 +/- 3 mEq/l. All patients were taking angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin-II receptor blockers (ARBs), 81% beta-blockers and 47% spironolactone. During follow-up, 5 patients died, 4 underwent heart transplantation and one received an implantable cardioverter-defibrillator. Five-year survival was 68%. CONCLUSIONS Five-year survival of our patients with FDCM, under optimal medical therapy, was similar to that of other forms of nonischemic DCM reported in the literature.