The advances in surgical and interventional treatment of congenital heart diseases have allowed a large number of patients with congenital heart disease to attain the adult age. This population involves almost 0.3/1000 of the total population in Western Europe and North America and can be estimated to be 25,000 patients in Italy. Patients with operated tetralogy of Fallot, benign forms of pulmonary atresia with ventricular septal defect, simple or complex transposition of the great arteries usually survive beyond childhood. These patients may need repeat interventions to treat lesions of native or reconstructed pulmonary arteries and/or aortic arch, to occlude residual shunts, to treat pulmonary incompetence. More complex heart diseases such as single ventricle, rarely allow survival until the adult age. The majority of these patients undergo heart transplant, often made difficult by multiple cardiac surgical interventions, anomalies of the pulmonary arteries, chronic cyanosis, and aorto-pulmonary shunts. Patients with relatively simple or complex congenital heart diseases need to be followed in specialized units, like those existing in the United States, Canada, and Great Britain.