It is possible that the relationship of social status to coronary heart disease is partly mediated through health-related behaviours that have been found to relate to both social status and CHD. Changes in certain health-related behaviours are known to lead to changes in CHD incidence. What are the characteristics of men who change or do not change these behaviours and their subsequent chances of CHD? This study aims to relate changes in men's CHD-related behaviours over a seven-year period to their social and demographic characteristics.A survey was carried out on a random sample of adults in Great Britain in 1984-85 and the equivalent information was obtained again on those participants who were re-interviewed seven years later in 1991-92. Results are presented for the 582 men aged 18-34 and the 584 men aged 35-49 at the first interview who were re-interviewed seven years later. Changes over the seven years in smoking, saturated fat intake, alcohol consumption and exercise were related to social and demographic factors. The two age groups showed broadly similar patterns of behaviour. In both age groups, those who continued with or took up a low fat diet and/or exercise were more likely to be in a higher social class, in employment, to live in private housing and to have more educational qualifications. For the younger men only, those in private housing were more likely to reduce the amount they smoked. Other findings are also reported. The findings suggest that those people who are in less advantageous social and economic situations are less likely to change to a more healthy lifestyle and so should be a focus for health education.