A predominantly right ventricular variant of isolated noncompaction cardiomyopathy is a potentially lethal disease entity, which only recently has become recognized in the clinical and cardiac imaging literature. There are currently few established morphologic criteria for the diagnosis other than right ventricular dilation and presence of excessive regional trabeculation. To date, there have been no autopsy reports of cases following either clinical diagnosis or sudden death. We report 2 adult cases of sudden unexpected death in which unexplained right ventricular dilation and prominent apical hypertrabeculation were the principal findings. The gross and microscopic results suggest pathological similarities between, or coexistence of, right ventricular noncompaction and arrhythmogenic right ventricular cardiomyopathies.