This is a survey of genetic metabolic diseases in which cardiomyopathy is typical or can be the leading symptom in infancy. Apart from the well-known Pompe disease, several other storage disorders, mitochondrial disorders, and miscellaneous conditions (particularly the carnitine deficiency syndromes) may be seen in this way. Since prompt diagnosis may be mandatory for genetic counselling, and sometimes for specific treatment, guidelines for clinical, cardiological, and laboratory work-up are given.