'Men born in 1914', from Malmö, Sweden, is a cohort study of the morbidity and mortality of cardiovascular diseases among 68-year-old men in an urban population. Ambulatory long-term ECG recording was part of the health examination that these men were invited to undergo in 1982. Five hundred attended (80.5%) of the 621 invited. Ninety-eight of the 394 men in whom the ECG recording was technically satisfactory had at least one episode with horizontal or downsloping ST segment depression greater than or equal to 0.1 mV. The median total duration of ST segment depression was 135 min. 90% of these episodes were not preceeded by any increase in heart rate. In only eight of the 47 men who reported an occurrence of chest symptoms during the recording period did ST segment depression and chest symptoms occur simultaneously. 43 months after the health examination, 33 (8.4%) men had died. The mortality in men without ST segment depression and without any history of coronary heart disease was 6.5%. The incidence of fatal and non-fatal myocardial infarction in men without ST depression greater than or equal to 0.1 mV and without a history of IHD was 2.3%. Men with ST depression greater than or equal to 0.1 mV in comparison with this group had a 4.4 times greater relative risk. The risk in men with both ST segment depression greater than or equal to 0.1 mV and history of coronary heart disease was 16.0 times greater. This study shows that asymptomatic ST segment depression is a frequent finding in elderly men. The occurrence of asymptomatic ST segment depression is associated with an increased cardiovascular mortality. This increased mortality is independent of a history compatible with angina pectoris or previous myocardial infarction.