Introduction. Tobacco smoking, which usually begins in teen- age, is one of the most important lifestyle risk factors for chronic diseases and a major public health problem worldwide. The aims of the study were to determine the prevalence of tobacco smoking and the mean age of initiation among adolescents in Genoa (Italy) and to identify some socio-demographic predictors that could be associated with the onset of smoking. Materials and methods. 2,301 randomly selected students (14- 19 years old) in Genoa completed an ad hoc questionnaire. The Kaplan-Meier method was used to evaluate the instantaneous risk of experimenting with smoking. A multivariate logistic regression model was used to determine whether current or previous smoking status was associated with socio-demographic characteristics. Results. 59.5% of respondents had tried smoking, while 35.6% defined themselves as current smokers. No difference in current smoking prevalence emerged between males and females (35.2% and 35.9%, respectively, p = 0.83). The mean age on initiation was 13.5 years for males and 13.9 years for females. The instantaneous probability of trying smoking changed with age, reaching a maximum at 14 years. Subjects who tried smoking before this age were more inclined to con- tinue smoking. The probability of being a current smoker was significantly higher among students from unmarried-parent families and those attend- ing vocational and technical secondary schools. Conclusions. There is a great need for the activation of new health promotion interventions and enforcement of those already existing, in order to raise awareness of the damage caused by smoking among adolescents, especially those belonging to high- risk groups.