The aim of the study was to explore sudden cardiac death during physical activity in young adults in Norway. This retrospective study examined adults aged 15-34 years during the period 1990-1997. The Cause of Death Registry was used to identify cases of sudden cardiac death in sports. These cases were validated with information from medical records and autopsy reports. Twenty-three sports-related sudden deaths (22 men), mean age 27 years (17-34 years), were identified. Causes of death were myocardial infarction (11), myocarditis (5), conduction abnormalities (2), aortic stenosis (1), cardiac rupture (1), hypertrophic obstructive cardiomyopathy (1), congenital coronary anomaly (1), and coronary sclerosis without defined infarction (1). The deaths were distributed across different types of sports activities. The incidence of deaths among physically active young men was 0.9 per 100,000. The number of myocardial infarctions is higher than expected. The incidence is similar to that found in other studies. A vast majority of the cases of death were men.