Cardiomyopathy often has devastating consequences in children. This Australian study found an incidence of 1.24 cases per 100,000 person-years at risk from 1987 to 1996 among children under 10. Among cases of dilated cardiomyopathy, lymphocytic myocarditis was an important cause. Hypertrophic cardiomyopathy was about half as common as dilated cardiomyopathy. A myocardial disorder known as left ventricular noncompaction was also found. A study in Australia and a study in the United States define the magnitude of the problem. The pediatric cardiomyopathies are an uncommon and heterogeneous group of disorders accounting for about half of all cardiac transplantations in children. 1 Studies of childhood cardiomyopathy usually reflect the experience at a single institution 2 – 5 or in a single region. 6 , 7 A better understanding of the epidemiology, causes, and outcomes of childhood cardiomyopathy would facilitate planning and provision of medical services. The centralization of Australian pediatric tertiary services provides an opportunity to examine the incidence and natural history of rare conditions. This report describes epidemiologic observations from a retrospective, population-based cohort study of all Australian children who presented with cardiomyopathy over . . .