Objective-To assess to what extentNordic parents strive to protect their children from environmental tobacco smoke (ETS) at home. Design-A cross-sectional study using an anonymous questionnaire. Subjects and setting-A stratified, random sample of 5500 households containing a child born during 1992, including 1500 households in Denmark and 1000 households in each of the countries of Finland, Iceland, Norway, and Sweden. Main outcome measures-Smoking status of parents, prevalence and magnitude of weekly ETS exposure, rules regarding smoking in the home. Results-82% of current smokers reported having tried to change their smoking behaviour for the sake of their children. Of all parents who answered the questionnaire, 75% reported having introduced some rules to limit ETS in their home. In households where at least one parent smoked, 57% reported that children were exposed to ETS at home. Child exposure to ETS was most prevalent in single-parent households and in households in which parents had lower levels of education. However, these parents were not less likely than other smoking parents to report having tried to change their smoking behaviour for the sake of their children. Conclusion-Environmentaltobacco smoke at home is still a problem for many children in the Nordic countries. However, most smoking parents reported having made eVorts to change their smoking behaviour for the sake of their children; and in approximately half of all households containing at least one daily smoker, parents reported protecting their children from ETS exposure in the home. Although actual exposure may be higher owing to possible under-reporting of ETS, our results indicate a general awareness in the Nordic countries of the potential negative eVects of ETS on children. (Tobacco Control 1998;7:56-60)