Our aim was to describe socio-economic and behavioural factors related to caries experience in school children in Sassari, Sardinia (Italy). Four hundred and three 12-year-old schoolchildren were randomly selected and their teeth clinically examined after air drying, under standard light using a plain mirror and WHO community periodontal index for treatment needs (CPITN) ballpoint probe. The clinical DMFS index was recorded following a diagnostic threshold, CPITN following the WHO indications. A questionnaire concerning oral hygiene habits (OHH), the onset of toothbrushing habits (OTH), frequency of dental check-ups (DCU), sweet food and soft drink consumption and socio-economic background factors, i.e. parents' occupational status (SOCFAM) and parents' age, was filled in by children and parent(s)/guardian(s). The caries prevalence was 61.6%. A positive skewness of DMFS was observed. Regarding caries, a significant linear trend (p<0.05) was found among odds ratios at each exposure level in SOCFAM, OHH, OTH and CPITN. A logistic regression model for caries was constructed using related factors. CPITN (gingival conditions) gave a significant contribution in the predictive model (p = 0.01). Gender acted as an effect modifier on CPITN, so logistic regression models were constructed for males and females separately. CPITN was the only statistically significant covariate in males and OHH the only one in females. Our results confirm a high caries prevalence and also a need for preventive and educational programmes for caries in Sardinia.