Objetive: To analyze the variables related to smoking initiation among adolescent students in two high schools (one public and one private) in the city of Belém, Brazil, in 2005. Methods: An anonymous self-report questionnaire - comprising 27 closed questions regarding smoking experimentation, smoking habit, access to buying cigarettes, reasons for smoking experimentation, self-perception regarding academic performance, conversations about smoking with the family, and socioeconomic level - was used for data collection. The study comprised 1520 students: 724 (47.6%) from the private school and 796 (52.4%) from the public school. Results: Mean age of participants was 16.5 years. Of the 1520 students evaluated, 669 (44%) reported experimenting with smoking, and 11% smoked regularly. In the public school and the private school, respectively, 51.2% and 36.7% of the participants had experimented with smoking (p = 0); 14.6% and 7%, respectively, were regular smokers (p = 0). We found that, in both schools, the following factors were associated with smoking initiation and current smoking: curiosity, presence of smokers as social contacts, not being praised for not smoking, and perceiving oneself as having poor or mediocre academic performance. Socioeconomic level was found to be associated with experimentation and current smoking only among experimenters of higher socioeconomic classes (A and B) in the private school. Conclusions: Among the students evaluated, the variable most closely associated with smoking was curiosity. Experimentation and regular tobacco use were more common in the public school than in the private school.

Keywords: Smoking; Epidemiologic factors; Students.