Smoking is more prevalent among lower socioeconomic status groups, among those who perceive economic difficulties and among lone mothers. Less is known of how these factors contribute to smoking independently. The aim of this study was first to examine the association between smoking and both economic difficulties and lone parenthood. We then also studied to what extent smoking among people experiencing economic difficulties and lone parenthood is due to other factors such as socioeconomic status and social relations. The data derive from surveys conducted among the employees of the City of Helsinki, Finland, in 2000 and 2001 including 6243 respondents aged 40-60 yr (response rate 68%). The measures were daily smoking, economic difficulties and family type, as well as socioeconomic status (education, occupational social class, household income, housing tenure) and social relations. The more had respondents experienced economic difficulties, the more prevalent was their smoking. Smoking among lone parents was more common than among parents living together; this was true for both men and women. After controlling for socioeconomic status and housing tenure, the association between smoking and economic difficulties, as well as that between smoking and lone parenthood, attenuated but remained statistically significant. However, after controlling for social relations the associations became stronger. Both economic difficulties and lone parenthood were associated with smoking independent of education, occupational social class, household disposable income, housing tenure or social relations for both men and women.