ObjectiveTo study the net economic effect of smoking on society.DesignProspective cohort study.SettingEastern Finland.PatientsWe studied mortality, paid income and tobacco taxes, and the cumulative costs due to pensions and medical care among tobacco smoking and non-smoking individuals in a 27-year prospective cohort study of 1976 men from Eastern Finland. These individuals were 54–60 years old at the beginning of the follow-up.Main outcome measuresThe net contribution of smoking versus non-smoking individuals to public finance balance (euros).ResultsSmoking was associated with a greater mean annual healthcare cost of €1600 per living individual during follow-up. However, due to a shorter lifespan of 8.6 years, smokers’ mean total healthcare costs during the entire study period were actually €4700 lower than for non-smokers. For the same reason, each smoker missed 7.3 years (€126 850) of pension. Overall, smokers’ average net contribution to the public finance balance was €133 800 greater per individual compared with non-smokers. However, if each lost quality adjusted life year is considered to be worth €22 200, the net effect is reversed to be €70 200 (€71.600 when adjusted with propensity score) per individual in favour of non-smoking.ConclusionsSmoking was associated with a moderate decrease in healthcare costs, and a marked decrease in pension costs due to increased mortality. However, when a monetary value for life years lost was taken into account, the beneficial net effect of non-smoking to society was about €70 000 per individual.