Background Differences between socioeconomic groups in mortality from and risk factors for cardiovascular diseases have been reported in many countries. We have made a comparative analysis of these inequalities in the United States and 11 western European countries. The aims of the analysis were (1) to compare the size of inequalities in cardiovascular disease mortality between countries, and (2) to explore the possible contribution of cardiovascular risk factors to the explanation of between-country differences in inequalities in cardiovascular disease mortality. Data and Methods Data on ischaemic heart disease, cerebrovascular disease and total cardiovascular disease mortality by occupational class and/or educational level were obtained from national longitudinal or unlinked cross-sectional studies. Data on smoking, alcohol consumption, overweight and infrequent consumption of fresh vegetables by occupational class and/or educational level were obtained from national health interview or multipurpose surveys and from the European Union's Eurobarometer survey. Age-adjusted rate ratios for mortality were correlated with age-adjusted odds ratios for the behavioural risk factors. Results In all countries mortality from cardiovascular diseases is higher among persons with lower occupational class or lower educational level. Within western Europe, a north–south gradient is apparent, with relative and absolute inequalities being larger in the north than in the south. For ischaemic heart disease, but not for cerebrovascular disease, an even more striking north–south gradient is seen, with some ‘reverse’ inequalities in southern Europe. The United States occupy intermediate positions on most indicators. Inequalities in cardiovascular disease mortality are associated with inequalities in some risk factors, especially cigarette smoking and excessive alcohol consumption. Conclusions Socioeconomic inequalities in cardiovascular disease mortality are a major public health problem in most industrialized countries. Closing the gap between low and high socioeconomic groups offers great potential for reducing cardiovascular disease mortality. Developing effective methods of behavioural risk factor reduction in the lower socioeconomic groups should be a top priority in cardiovascular disease prevention.