Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a clinically and genetically heterogeneous heart muscle disorder associated with ventricular arrhythmias and risk of sudden death. The disease is heredo-familial, and mutations in desmosomal genes have been identified in about half of patients. Recent experimental models confirm this disease develops after birth due to progressive myocardial dystrophy. Genotype-phenotype correlations, including magnetic resonance and pathology studies on heart specimens, are currently demonstrating that the spectrum of the disease is wider than initially thought and usually referred to with the adjective "right ventricular", with the evidence of biventricular or even isolated left ventricular forms, so that it is increasingly identified simply as "arrhythmogenic cardiomyopathy". A revision of the diagnostic criteria encompassing familial, electrocardiographic, arrhythmic, morpho-functional and histopathologic findings, has been made to improve diagnostic sensitivity and specificity, in particular of the concealed forms and left-dominant subtypes of the disease. Experimental models are mandatory to gain an insight into the cascade of cellular and molecular events leading from gene defect to myocardial dystrophy in ARVC.