RESUMEN
BACKGROUND: As the exact prevalence of oral alterations in children is still not known and the findings are controversial, other studies about this subject are necessary. METHODS: A cross-sectional survey was carried out on 1211 Brazilian children divided in two age groups: 0-4 and 5-12 years. The patients were economically classified and data of medical history were obtained from medical records. RESULTS: The frequency of children presenting alterations was 27.0%, and it was higher in older children. The most common lesions were geographic tongue, cheek biting, and melanotic macule. Candidiasis was associated with antibiotic therapy and use of pacifiers. Fissured tongue was associated with congenital anomalies, allergy; age from 5 to 12 years. There was a lack of association of patient's economic status and prevalence of oral mucosal alterations. CONCLUSIONS: The frequency of mucosal alterations in children is high and increases with age, and some of them are associated with habits and medical history of the patients.