study in Monastir, Tunisia estimated the prevalence of smoking and analysed the determinants of tobacco use among adolescents aged 10–19 years. An observational cross-sectional study was performed in the 8 colleges and high schools of Monastir city in 2004. The mean age of the 900 respondents was 15.8 (SD 2.2) years and 47.7% were aged under 16 years. The overall prevalence of cigarette use during the past year was 16.0% (30.2% among males and 4.6% among females). The first smoking experience was initiated by friends in 45.8% of cases, at a mean age of 13.8 (SD 2.3) years. One-fifth of smokers (21.5%) had used other forms of tobacco. In multivariate analysis, male sex, academic failure, poor family management, antisocial behaviour and addictive behaviour were the main predictors of adolescent smoking status. The prevalence of smoking among adolescents in Monastir is high and requires targeted action.