Sudden death of an athlete is the most devastating medical event in sports. While accidents account for more than 50% of these cases, sudden cardiac deaths (SCD) are less frequent (approx. 15%), but the leading medical cause of deaths. The risk depends on age, sex, ethnicity, type of sport and sport level. There are large variations in the methods of registration of SCD in recreational and competitive sports. This must be taken into account when interpreting reported incidences and causes. High data quality in registries is a prerequisite for meaningful preventive strategies (e.g. ECG screening and safety at sports facilities).