Mortality from coronary heart disease (CHD) is higher in manual than in non-manual occupational classes and is higher in Scotland, Wales, and the North of England than in the South. Trends in these inequalities were examined in the light of the decline in CHD mortality in Great Britain. With the use of 1979/83 death rates as standard, mortality ratios (SMRs) for all causes, lung cancer, CHD, and cerebrovascular disease in 1979/83 were compared with SMRs in 1970-72. Despite the general fall in mortality the relative disadvantage of manual compared with non-manual classes has increased for each of these 4 cause groups. The regional differences in CHD mortality persist. Among men, in every region of Great Britain, CHD mortality has declined in non-manual classes. Only in Wales has there been an appreciable decline in CHD mortality in manual classes. Among women, lung cancer and CHD mortality have fallen in non-manual classes but have increased in manual classes. Differences in smoking between social classes are likely to be important. Other differences in behaviour may be important, but the effect of unemployment and increased income differentials should also be explored.