This article discusses recent advances in the pathology and pathogenesis of arrhythmogenic cardiomyopathy (AC) that have led to the current perspective of a genetically determined cardiomyopathy. AC was initially believed to be a developmental defect of the right ventricular (RV) myocardium, thus justifying the original designation of dysplasia. Only in the 1980s was AC recognized to be a heredofamilial heart disease, usually transmitted as an autosomaldominant traitwith variablepenetrance. Nowadays, up to50%ofprobandsaffectedwithAC carry 1 or more mutations in genes encoding desmosomal proteins.