Background. A clear, up-to-date picture of smoking prevalence and its determinants is needed to inform the development of an effective tobacco control policy in Ukraine, particularly given the way in which the tobacco industry has targeted post-Soviet countries since transition. Methods. A nationally representative household survey was undertaken in Ukraine in February 2000. Results. Data were available on 1,590 individuals (response rate 72%). Fifty-seven percent of men an 10% of women were current smokers and an additional 21 and 7%, respectively, were ex-smokers. Smoking behavior has changed considerably over successive generations, with an increase in the proportion of women smoking and a reduction in the mean. age at first smoking. Factors associated with smoking include young age, urban residence (among women), and material hardship, particularly unemployment. Involvement in social networks appears to reduce the probability of smoking. Smoking commonly occurs in public places and smokers differ from nonsmokers in their health beliefs about smoking. Conclusions. Levels of smoking among men are already high and among young women are increasing rapidly. Unless an effective tobacco policy response is developed to address the issues identified, tobacco will continue to make an increasingly large contribution to premature morbidity and mortality in Ukraine. (C) 2001 American Health Foundation and Academic Press.