Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a cardiac disease characterized by progressive myocardial atrophy and fibrofatty replacement. Standard electrocardiograms (ECGs) and signal-averaged ECGs (SAECGs) were relatively low cost and repeatable diagnostic tools. In this study, ECGs and SAECGs of patients with ARVC were analyzed with the aim to assess the diagnostic capability of these noninvasive techniques. A total of 205 patients with ARVC were analyzed. ECGs were abnormal in 74% of patients and SAECGs were positive in 60%, with normal ECGs mostly related to mild forms of the disease. The most common electrocardiographic abnormalities were localized right QRS prolongation, poor r wave progression in the right precordial leads, incomplete right branch bundle block, prolonged S-wave upstroke in V(1) to V(3), parietal block, ST-segment elevation in V(1) to V(3), inversion of T waves beyond V(2), and epsilon wave. Low QRS voltages in the precordial leads were frequently present in all patients with ARVC compared with a group of 120 healthy subjects (p = 0.00001). T-wave inversion beyond V(3) characterized subjects with severe right ventricular dilatation, whereas in subjects with left ventricular involvement, T-wave inversion in lateral leads was more commonly detected. Overall, the extent of electrocardiographic abnormalities was related to disease extent. In conclusion, abnormalities in ECGs and SAECGs were frequent in patients with ARVC and correlated with disease extent, even if a stereotypical electrocardiographic pattern did not exist. ECGs and SAECGs remain an important tool for the diagnosis and assessment of ARVC extent. Nonetheless, a normal ECG does not exclude the presence of the disease.