Coronary heart disease risk factors and circumstances of death were examined in 258 people who were a representative sample of all persons, less than 70 years of age, dying suddenly and unexpectedly in Auckland during the twelve month period from 1 March 1981. From this sample we identified nine individuals who had been running regularly for more than three months prior to death. All those identified were men aged between 35 and 56 years, all had historical evidence of abnormal coronary heart disease risk factors and six were known to have had symptomatic cardiovascular disease. Seven of the nine died during or within 30 minutes of exercise and eight of the nine had postmortems showing severe coronary artery disease.