The Scottish Heart Health Study was conducted in response to a report by a Working Group of the Chief Scientist Organisation and followed an initial of the Cardiovascular Epidemiology Unit. The aims of the study were to establish the levels of coronary risk factors in Scotland, to determine the extent to which these risks factors explained the geographical variation in coronary heart disease, and their relative contribution to the prediction of coronary heart disease in a cohort of men and women.The Scottish Heart Health Study is a study of lifestyle and coronary heart disease risk factors in 10 359 men and women aged 40-59 years, in 22 districts of Scotland. The study was conducted in 1984-86, when Scotland had the highest national coronary mortality reported by the World Health Organisation. The study employed standardised methods emphasing quality e4 control based on a World Health Organisation protocol to allow comparisons in place and time, and therefore to provide a definitive baseline against which interventions can be assessed. The cross sectional aspect of the study has been analysed and addresses the first two study objectives. The third objective will only be achieved when sufficient prospective coronary events have occurred.Current cigarette smokers constitute 39% of men and 38% of women, higher levels than those reported in England but lower than previous Scottish reports. Considerable variation in smoking was noted across the study districts from 29% to 52% in men. Mean blood pressure levels were 134/84 mmHg for men and 131/81 mmHg in women, these levels are lower than previous studies in Britain and there was a narrow range of levels across the districts. Mean levels of blood cholesterol were 6.4 mmol/l in men and 6.6 mmol/l in women - as high as other British studies and high by international standards. There was little geographical variation in blood cholesterol noted.High levels of blood cholesterol and cigarette smoking provide a classical explanation for the excess coronary deaths in Scotland, justifying action, but other factors, such as dietary deficiencies, also merit further investigation. The geographical variation in coronary mortality can best be explained by a group of risk factors which all show a social gradient and these include cigarette smoking, physical activity, blood pressure, and the consumption of alcohol, fruit and green vegetables.