AIMS: To describe levels of knowledge on the harmful effects of tobacco and public support for tobacco control measures in nine countries of the former Soviet Union and to examine the characteristics associated with this knowledge and support. METHODS: Standardised, cross-sectional nationally representative surveys conducted in 2010/2011 with 18 000 men and women aged 18 years and older in Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia and Ukraine. Respondents were asked a range of questions on their knowledge of the health effects of tobacco and their support for a variety of tobacco control measures. Descriptive analysis was conducted on levels of knowledge and support, along with multivariate logistic regression analysis of characteristics associated with overall knowledge and support scores. RESULTS: Large gaps exist in public understanding of the negative health effects of tobacco use, particularly in Azerbaijan, Kazakhstan, Kyrgyzstan and Moldova. There are also extremely high levels of misunderstanding about the potential effects of 'light' cigarettes. However, there is popular support for tobacco control measures. Over three quarters of the respondents felt that their governments could be more effective in pursuing tobacco control. Higher levels of education, social capital (membership of an organisation) and being a former or never-smoker were associated with higher knowledge on the health effects of tobacco and/or being more supportive of tobacco control measures. CONCLUSIONS: Increasing public awareness of tobacco's health effects is essential for informed decision-making by individuals and for further increasing public support for tobacco control measures.