Coronary heart disease (CHD) has traditionally been regarded as a male disease and, because of this, the magnitude of the problem in women is often overlooked. Yet, cardiovascular disease (CVD) and CHD in particular, remains, next to cancer, the leading cause of morbidity and mortality in women. The longstanding emphasis on the problem of CHD in men, has resulted in a widespread tendency to minimise the incidence and severity of the disease in women. Moreover, most epidemiologic studies examining morbidity and mortality from CHD have focused largely on men, producing a significant gender gap in the research. The lack of information on CHD risk factors and prevention of heart disease in women in Britain is of particular concern, given that British women have one of the highest rates of coronary disease in the world. The Marks and Spencer Coronary Risk Factor Study (MSCRFS) is a cross-sectional and prospective study of CHD risk factors in female employees of the Marks and Spencer retail organisation. The present study is confined to an analysis of cross-sectional data from 14,077 women screened between June 1988 and July 1991. The prevalence and distribution of a variety of lipid, lipoprotein, biochemical, anthropometric and lifestyle-related CHD risk factors among women in the United Kingdom is described, together with their key interrelationships. In addition, the metabolic impact of exogenous hormones, specifically oral contraceptives and postmenopausal hormone replacement, is described. This study - the largest of its kind in the UK - provides reference ranges for a wide range of CHD risk factors in women in the UK, and gives a unique insight into the impact of a variety of lifestyle-related factors on CHD risk. There is an enormous potential for reducing the very high risk of CHD among women in the UK, which needs to be addressed. Based on these data, health strategies designed to reduce morbidity and mortality from CHD can be planned and implemented more effectively.