Abstract This cross-sectional study aimed to determine the association between dental caries and weight status, and between dental caries and physical activity in Brazilian schoolchildren aged 8 to 12 years. A multi-stage sample of children enrolled in 20 private and public schools in 2010 in Pelotas, Southern Brazil, were invited to participate in the study. Socioeconomic data were collected from parents, and data regarding children characteristics were collected from children using a questionnaire and anthropometric measures. The Body Mass Index was obtained, and children were classified as overweight/obese considering age and sex. Dental examinations were performed to assess the presence of gingival inflammation, dental caries prevalence (DMFT≥1) and dental caries experience (mean DMFT). Multivariate Poisson Regression was used to assess factors associated with dental caries prevalence and experience. A total of 1,210 children were included in the study. Dental caries prevalence was 32.4% (95% CI 29.7-35.2), while the mean DMFT was 0.64 (± SD 1.00). Children who practiced less than 300 minutes per week of physical activity and overweigh/obese children had lower prevalence of dental caries, while children with obesity or overweight presented lower dental caries experience. Obesity/overweight and physical activity level presented an inverse relationship with dental caries. Longitudinal studies investigating the complexity of this relationship are required.