Objective: This study estimated the prevalence, extent, buccal distribution and associated factors involving enamel defects in Brazilian schoolchildren. Study design: A cross-sectional study using a multistage cluster random sample of 1,206 8-12-year-old Brazilian schoolchildren was carried out in Pelotas, Brazil. The prevalence of enamel defects in the permanent dentition was determined using the modified Developmental Defects of Enamel index (DDE). Sociodemographic and health data were collected from their mothers using a semi-structured questionnaire. Data were analyzed using Poisson regression modelling for DDE prevalence and negative binomial regression modelling for the extent of DDE. Results: The prevalence of any enamel defects was 64.0% (95% Confidence Interval: 61.4, 67.0); the main types were diffuse opacities (35.0%), demarcated opacities (29.5%) and hypoplasia (3.7%). In general, older children had a lower prevalence and extent of enamel defects than their counterparts (p<0.001). There were no other significant associations. Conclusion: Enamel defects are common, especially among younger children, but the role of pre-, peri- and postnatal exposures remains unclear.