Sudden death (SD) in childhood is rare, representing only 10% of paediatric mortality after one year of age. The individual risk is estimated between 1 in 20.000 and 1 in 50.000 per year. In case of a negative autopsy for cardiac morphologic anomalies, the most presumable cause remains a genetically-determined malignant primary ventricular arrhythmia. Rhythmic sudden cardiac death can be categorized as a complication of a cardiomyopathy (dilated or hypertrophic), or as a primary channelopathy without any structural heart disease. Primary ventricular arrhythmias include long QT syndrome, Brugada syndrome, short QT syndrome and Polymorphic Ventricular Tachycardia. The diagnosis of such syndromes relies upon specific ECG anomalies, personal history of family members, eventually echocardiography and drug challenge. For some of these diseases, morbid genes have been identified thus rendering possible the management of pre symptomatic or undiagnosed family members within specialized multidisciplinary teams. In case of sudden arrhythmic death in children, the parents and siblings must be examined Rescued sudden death exposes to a high risk of recurrence. In such patients, the automatic implantable defibrillator has dramatically improved survival.