Aims: To identify factors, which were related to being smoke-free and snus-free, respectively, among adolescents in relation to adolescents who were smoking and/or using snus, and de-termine if there were any sex differences. Me- thods: A questionnaire study was performed among students in year two in upper secondary schools (17-years-old) in southern Sweden in 2009. More than 2200 students completed the questionnaire regarding health and living habits anonymously. The variables were tested by χ²-test, before selection into the logistic model. Because of the salutogenic approach in the study, the results of the logistic regression analyses were expressed as Positive Odds Ratio (POR). Results: The prevalence of being smoke- free was 75.6 percent for girls and 70.2 percent for boys, whilst the prevalence of being snus- free was 95.1 percent for girls and 70.2 percent for boys. Having a tobacco-free best friend was the most important factor that correlated with being smoke- and snus-free as an adolescent, for both boys and girls. Good living habits, such as drinking less alcohol, were also central to being smoke-free and snus-free. Conclusions: The results show that a tobacco-free environ-ment has a great influence on whether or not adolescents stay tobacco-free. As the environ-ment has a big impact, the school has a big challenge to work with the school environment and policies but also with family responsibility, norms and attitudes to tobacco.