Norwegian counties show considerable variations in their rates of mortality from arteriosclerotic heart disease. These variations cannot be explained by present-day differences in standard of living. Such differences did exist in the past as was shown by large variations in infant mortality. A significant positive correlation has been found between the county age-adjusted mortality from arteriosclerotic heart disease in people aged between 40 and 69 years and county infant mortality relating to the early years in the same cohorts. The findings suggest that great poverty in childhood and adolescence followed by prosperity, is a risk factor for arteriosclerotic heart disease.