Background:
Smoking is declining, but in most countries lower educated smoke more than higher educated. Our aim was to examine development with these differences in a country with strict tobacco control policies, Finland.

Methods:
We used annual population-based random sample data of 25-64 year-olds from 1978-2016 (N=104,317). Response rate varied between 84% and 40% during the study period. We used relative education as a measure for socioeconomic position. For each year education was stratified into tertiles, and low and high educated were included in further analysis. The outcome variable was daily smoking. Weights were used in order to enhance the population representation. Prevalence figures and logistic regression analysis were used.

Results:
At the start of the study period, 40% of lower educated men and 33% of higher educated men smoked. For women, the corresponding proportions were 18% and 13%, respectively. Smoking decreased in each educational group except lower educated women. Preliminary analyses suggest that, compared with the time period before 2009, all population groups except lower educated women were less likely to smoke after 2009. In the 2010s, educational differences in smoking slightly declined both among women and men due to a more prevalent decline in smoking among lower educated. In 2016 among men, 26% of lower educated smoked, while 6% of higher educated smoked. Among women corresponding proportions were 19% and 9%.

Conclusions:
Smoking has declined both among lower and higher educated and socioeconomic differences diminished in the 2010s in Finland. However, educational differences in smoking are still marked, which underlines the need for further actions reducing the overall public impact of these differences. Further analyses will test relative differences in smoking among socioeconomic groups and careful sensitivity analyses will be conducted to validate the results.