Objective: To assess the relationship between caries prevalence and toothbrushing and dietary habits in adolescents in the city of Milan (Italy). Research Design: The study consisted of a cross-sectional survey using clustering samples. DMFT was recorded following the WHO guidelines by three calibrated examiners. A dental health questionnaire was completed by the subjects to assess their toothbrushing and oral hygiene habits. Univariate and multivariate analysis were performed. Participants: A sample of 1,333 students (age-range 13-18 years, 648 males and 685 females) was studied. The students came from three secondary schools located in different socio-economic and cultural areas of the city. Results: Caries experience (DMFT>0) was 59.11%. A significant linear trend (p<0.01) was observed for DT>0 among the three different schools selected. The mean DMFT was 1.94 ± 2.46 and difference observed in DT, FT and DMFT among the three schools was statistically significant (p<0.05). Eating snacks more than once a day provided a significantly higher odds ratio for DMFT>0 and for DT>0 (OR=5.24, p<0.001 and OR= 1.46, p=0.01 respectively). Conclusions: A significant trend between caries experience and socioeconomic status was observed: adolescents, attending school in a low-socio-economic areas, showed higher caries prevalence and higher levels of untreated caries than their counterparts attending schools located in medium-high socio-economic areas. Key words: Caries epidemiology, dmft index, cross-sectional study, adolescents, Italy.