Sudden cardiac arrest is most often the first clinical manifestation of an underlying cardiovascular disease and usually occurs in previously asymptomatic athletes. The risk benefit ratio of physical exercise differs between young competitive athletes and middle-age/senior individuals engaged in leisure-time sports activity. Competitive sports are associated with an increase in the risk of sudden cardiovascular death (SCD) in susceptible adolescents and young adults with underlying cardiovascular disorders. In middle-age/older individuals, physical activity can be regarded as a 'two-edged sword': vigorous exertion increases the incidence of acute coronary events in those who did not exercise regularly, whereas habitual physical activity reduces the overall risk of myocardial infarction and SCD. Although cardiovascular pre-participation evaluation offers the potential to identify athletes with life-threatening cardiovascular abnormalities before onset of symptoms and may reduce their risk of SCD, there is a significant debate among cardiologists about efficacy, impact of false-positive results and cost-effectiveness of routine screening. This review presents an appraisal of the available data and criticisms concerning screening programmes aimed to prevent SCD of either young competitive athletes or older individuals engaged in leisure-time sports activity.