The prevalence and correlates of home smoking bans in the Republic of Korea were examined using population-based data from telephone interviews with 500 Seoul adult residents in 2002. Most (97%) respondents indicated that they smoked, or that their spouse, other family member, or a regular friend smoked. Nearly all indicated that environmental tobacco smoke (ETS) is harmful. Only 19% of homes banned smoking, 65% allowed smoking anywhere, and 16% allowed smoking by special guests or in certain areas. The odds of having a full ban were significantly greater for men, married individuals, those less than 35 years or more than 50 years of age, non-smokers, individuals whose nonspouse family members did not smoke, and individuals with more sources of anti-ETS messages. Home smoking bans should be promoted by media campaigns and other tobacco control activities, because knowledge of the effects of ETS was already high.