Development of the concept of "athlete's heart" is traced through early clinical and radiographic studies to modern echocardiography and magnetic resonance imaging. It is noted that the lower limits of criteria for the diagnosis of a "pathological" enlargement of the heart have frequently been revised in an upward direction, as the prevalence of large hearts has been recognised in both endurance and power sports competitors who are in good health. Belief that hypertrophic cardiomyopathy is the commonest cause of sports related death in young adults is traced to weak diagnostic criteria and frequent republication of a very small group of cases. Although the existence of a congenital myocardial dystrophy is now well established, this condition is extremely rare, and has no particular predilection for athletes. Genetically based screening tests may become available in the future, but the exclusion of young adults from sports participation on echocardiographic criteria appears costly and ineffective. For most people, the development of a large heart is not a pathological sign--rather, it is a desirable outcome that will enhance performance on the sports field, and will allow longer independence in old age.