Athletic activity is associated with an increased risk of sudden death for 
individuals with some congenital or acquired heart disorders. This review 
considers in particular the causes of death affecting athletes below 35 years of 
age. In this age group the largest proportion of deaths are caused by diseases 
with autosomal dominant inheritance such as hypertrophic cardiomyopathy, 
arrhythmogenic right ventricular cardiomyopathy, long QT-syndrome, and Marfan's 
syndrome. A policy of early cascade-screening of all first-degree relatives of 
patients with these disorders will therefore detect a substantial number of 
individuals at risk. A strictly regulated system with preparticipation screening 
of all athletes following a protocol pioneered in Italy, including school-age 
children, can also detect cases caused by sporadic new mutations and has been 
shown to reduce excess mortality among athletes substantially. Recommendations 
for screening procedure are reviewed. It is concluded that ECG screening ought 
to be part of preparticipation screening, but using criteria that do not cause 
too many false positives among athletes. One such suggested protocol will show 
positive in approximately 5% of screened individuals, among whom many will be 
screened for these diseases. On this point further research is needed to define 
what kind of false-positive and false-negative rate these new criteria result 
in. A less formal system based on cascade-screening of relatives, education of 
coaches about suspicious symptoms, and preparticipation questionnaires used by 
athletic clubs, has been associated over time with a sizeable reduction in 
sudden cardiac deaths among Swedish athletes, and thus appears to be worth 
implementing even for junior athletes not recommended for formal 
preparticipation screening. It is strongly argued that in families with 
autosomal dominant disorders the first screening of children should be carried 
out no later than 6 to 7 years of age.