The main objective of this study was to determine the impact of discussion within family about the harmful effects of smoking on intention to initiate smoking in the long term among nonsmoking adolescents.Data from Global Youth Tobacco Survey for 25 European countries were used. The outcomes of interest were, therefore, the intention to initiate smoking 1 and 5 years after the survey. Discussion within family about harmful effect of smoking was the main predictor with age, sex, and smoking status of parents, friends, and classmates as covariates. The association between predictors and outcomes was assessed through multiple regression analysis.A total of 118,703 nonsmoking adolescents were included. Within-family discussion significantly reduced the odds of intention to initiate smoking 1 and 5 years later. Intention to initiate smoking also was significantly associated with the smoking status of friends, classmates, and parents, except for father's smoking status, which was not associated with intention to initiate 1 year later.This study demonstrated that within-family discussion about the harmful effects of smoking may contribute to reduce the intention to start smoking among adolescents in the long term. Such a discussion was associated with reduced intention to smoke even when adjusting for parent/friend and classmate smoking.