In this study we analyse the trend in socio-economic differences in mortality from ischaemic heart and cerebrovascular diseases in the economically active male population aged 25-64 years in Spain and France. The data used were taken from deaths from these two causes in 1980-1982 and 1988-1990; in the case of Spain the data came from the Eight Provinces Study. Individuals were grouped into four categories - professional/managerial, clerical/sales/service workers, farmers, and manual workers - and the mortality rate ratio was estimated with reference to the professional/managerial group. For ischaemic heart disease in 1980-1982, professionals and managers aged 25-44 years had the lowest risk of mortality in Spain, and the highest risk of mortality in France; in 1988-1990 the socioeconomic differences in mortality in Spain increased, whereas the relation was inverted in France. In 1980-1982, professionals and managers aged 45-64 years had higher mortality from ischaemic heart disease than the other occupational groups in both countries; in 1988-1990 this relation was inverted, except in the case of clerical/sales/service workers in Spain. For cerebrovascular disease, manual workers experienced the highest mortality in the 25-44 year age group in 1980-1982, and the differences increased in 1988-1990 in all groups with respect to professionals and managers in both places. Professionals and managers in France and manual workers in Spain had the highest mortality between 45 and 64 years in 1980-1982; in contrast, in 1988-1990 professionals and managers had the lowest risk of mortality from this disease in both Spain and France, although in Spain the magnitude was similar to that of clerical/sales/service workers. In general terms, mortality from each disease was different in professionals and managers than in clerical/sales/service workers. Thus, the pattern of mortality and its evolution in different socio-economic groups cannot be analysed accurately when the two occupational groups are combined in a single large group of non-manual workers.