There are few studies regarding the clinical and instrumental presentation of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC); all available data derive from few specialized centers. We sought to describe clinical characteristics, instrumental findings and prognosis in a large cohort of patients (pts) with an ARVC diagnosis. From 1976 to 2006 all pts matching ARVC diagnostic criteria were enrolled in the Heart Muscle Disease Registry of Trieste and underwent a structured diagnostic protocol and follow-up. 104 pts were studied, 66% males, mean age 33±13 years; 84% were symptomatic at enrolment (mean duration 44±67 months); 75% had symptomatic arrhythmias (43% with previous sustained ventricular tachycardia or ventricular fibrillation (SVT/VF)), 36% syncope, 20% heart failure (12% in NYHA class III-IV). Familial ARVC were present in 46% of pts. ECG was abnormal in 72% (right bundle branch block 25%; epsilon potentials 15%; anterior negative T waves 51%; QRS dispersion >40ms 11%). At signal averaged ECG late potentials were present in 58% of pts. At 2D echo, mean right ventricle (RV) end-diastolic area was 30± 8 cm2 and RV fractional area contraction (FAC) 30±13%; RV aneurysms were present in 67%. RV systolic dysfunction (defined as FAC<40%) was present in 78%, characterized severe (FAC <30%) in 48%. Left ventricular systolic dysfunction was present in 27% of pts. Stress test was interrupted in 11% of cases for ventricular arrhythmias (55% SVT/VF). RV fibrofatty tissue was present in 52% of Nuclear Magnetic Resonance and in 59% of RV endomyocardial biopsy (performed respectively in 24 and 27% of pts). During a mean follow-up of 132±89 months, 3 pts were lost; 20 out of the remaining 101 pts (20%) experienced death/heart transplantation, 6 (3%) died for refractory HF; 4 pts (2%) underwent heart transplantation (HT); 6 pts (3%) died suddenly; one (0.5%) for extracardiac disease and 3 (1.6%) for unknown reason. Ten-year cumulative survival free from HT was 57%. In our population ARVC presentation was characterized by symptomatic, frequently sustained ventricular arrhythmias. Notably, LV involvement was present in approximately one third of pts at enrolment. In the long term, the overall prognosis was severe.