BACKGROUND We examined the relationship of smoking cessation in parents to smoking and uptake and cessation by their adolescent children. METHODS We analyzed a cross-sectional sample of 4,502 adolescents, ages 15-17 years, who lived in two-parent households that were interviewed as part of the 1992-1993 Tobacco Supplement of the Current Population Survey, which questioned householders 15 years of age and older about their smoking history. Ever smokers reported smoking at least 100 cigarettes in their lifetime. Former smokers were ever smokers who had quit. RESULTS Multivariate analyses, adjusted for demographic characteristics of adolescents, as well as father's age, education, and family income, found that adolescents whose parents had quit smoking were almost one-third less likely to be ever smokers than those with a parent who still smoked. Furthermore, adolescent ever smokers whose parents quit smoking were twice as likely to quit as those who had a parent who still smoked. Parental quitting is most effective in reducing initiation if it occurs before the child reaches 9 years of age. CONCLUSIONS Encouraging parents to quit may be an effective method for reducing adolescent smoking, through decreased uptake and increased cessation. The earlier parents quit, the less likely their children will become smokers.