Long-term intensive physical training leads to benign, physiological adaptive and morphological changes in the heart that is called „athlete’s heart“ (physiological enlargement of the heart). Changes include cardiac size, shape and function, increased left ventricular chamber size, wall thickness, volumes and mass. The extent to which LV dimension is increased in athletes is usually mild and usually remains within the accepted upper normal limits. The differential diagnosis of athlete’s heart and hypertrophic cardiomyopathy is of crucial importance, because sudden unexpected deaths may be the initial clinical event in young competitive athletes with hypertrophic cardiomyopathy, usually in relation to exertion, which have become highly visible events fueled by news media reports. Structural cardiovascular diseases are often clinically identifiable, including by a pre-participation screening. At present time there is no single approach that will definitively resolve this differential diagnosis in all instances, although several criteria appear useful and new techniques and methods promising in this regard.