Aim: To investigate the relationship between maternal depression and childhood caries in a cohort of adolescent mothers. Methods: This cross-sectional study nested in a cohort evaluated a sample of 538 mother/child dyads. When the children were 24-36 months of age, data regarding oral health from children and mothers were collected by clinical dental examination. A mother's major depressive disorder was assessed by using the Mini International Neuropsychiatric Interview (MINI [Plus]), at the current moment. Independent variables were obtained by using questionnaires. The outcome on dental caries experience was dichotomized by using 2 cut points: dmfs ≥1 and dmfs ≥3. Poisson regression analysis, using a hierarchical approach, was applied to assess the association between major depressive disorder in mothers with and those without caries experience and the outcome. Results: The prevalence of dental caries in children was 15.1% (n = 82). The mean dmfs index was 1.12 (SD = 3.72). The prevalence of major depressive disorder was 32.6% (n = 168). An interaction between caries status and depressive disorder was found, and after adjusted analysis, children from mothers with major depressive disorder with negative caries experience presented a higher caries prevalence (prevalence ratio 4.00, 95% confidence interval 1.29-12.41). Conclusion: Our findings suggest that maternal psychiatric disorders could have a negative impact on children's oral health.