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Background Exposure to smoking in movies has been linked with adolescent smoking initiation in cross-sectional studies. We undertook a prospective study to ascertain whether exposure to smoking in movies predicts smoking initiation. Method We assessed exposure to smoking shown in movies in 3547 adolescents, aged 10–14 years, who reported in a baseline survey that they had never tried smoking. Exposure to smoking in movies was estimated for individual respondents on the basis of the number of smoking occurrences viewed in unique samples of 50 movies, which were randomly selected from a larger sample pool of popular contemporary movies. We successfully re-contacted 2603 (73%) students 13–26 months later for a follow-up interview to determine whether they had initiated smoking. Findings Overall, 10 % (n=259) of students initiated smokin