Dilated cardiomyopathies occur mostly in infants and affect their vital and functional prognosis. They may be primary or secondary to various pathologies such as congenital cardiac malformation, toxic myocardial drugs or mucoviscidosis. Medical treatment may only be transiently effective and brutal or progressive aggravation may lead to cardiac transplantation being considered in those cardiomyopathies which are primary (without metabolic causes) or chronic secondary. Echocardiographic survey is the most efficient way to follow the evolution and to detect complications (cardiac thrombosis).