In several countries, the decline in smoking prevalence has been faster among the more educated groups compared with the less educated The aim of the study was to analyse self-reported smoking by years of education among Finnish men and women from 1978 to 1992. The data were collected annually by postal questionnaires from a random sample of 20–64-year-old Finns. Response rates varied between 68% (1985) and 86% (1978), averaging 79%, and the number of respondents between 3400 and 5107. Years of education were measured by questionnaire and categorized into two groups: <12 years and ≥12 years. Among men the prevalence of smoking has remained rather constant in both educational groups from 1978 to 1992. The difference between educational groups, however, diminished in the early 1980s but has increased again since 1984. Among women, those who had the less education slightly increased their smoking rates since 1985. The difference between the two female educational groups has increased. The less educated women have smoked as often or more often than the more educated men since the late 1980s. The decreasing smoking trends found in several other countries, relative to increasing levels of education, are being slowed. The results indicate that in smoking control policy more concern should be devoted to the less educated groups and to the efforts to prevent new cohorts from picking up the smoking habit.