Natural, sudden deaths in children are the cause of about 5% of all deaths. The most frequent cause appears to be pathology of the cardiovascular system. Direct cause of death are arrhythmias or, rarely, haemodynamic disturbance coexisting with decrease in minute cardiac output. Authors present the most frequent diseases (myocarditis, hypertrophic cardiomyopathy, long QT syndrome and preexcitations syndromes) as well as congenital heart defects (aortic stenosis, tetralogy of Fallot, transposition of the great arteries, Ebstein's syndrome, anomalies of coronary arteries) which can be causes of sudden death in childhood.