Long-term survival of patients with congenital heart disease has dramatically improved during the last 50 years and the number of adults with congenital heart disease is therefore increasing in all developed countries. Grown-up patients with congenital heart disease (GUCH) often present difficult and challenging problems. Patients with both native unoperated and operated malformations contribute to the GUCH population. Survivors without surgical treatment mainly have simple malformations; but a few have complex diseases, and some have survived with secondary pulmonary hypertension. Among operated malformations there are patients with a 'complete' repair (anatomical and physiological), others with a definitive palliation (physiological repair) and some with a simple palliation. The clinical spectrum is obviously diversified, depending on the underlying anomaly, surgical outcome, presence of residua, sequelae and/or complications, length of follow-up, comorbidities. Arrhythmias, bacterial endocarditis, cyanosis, polycythemia, heart failure, anomalies of pulmonary circulation, deterioration or malfunction of devices, need of cardiac and non-cardiac surgery, intercurrent non-cardiac diseases, and a need for cardiac and non-cardiac diagnostic procedures are common problems of adults with congenital heart disease. Physiological events such as pregnancy and childbearing deserve a careful multidisciplinary approach. While most simple native and well corrected GUCH do not require very specialized treatments throughout their life, the abnormalities and complexities of postoperative anatomy are often beyond the expertise of the adult cardiologist, requiring multidisciplinary competence in specialized tertiary centers. The problem is still unresolved and involves cultural, medical, technological and economically relevant issues.