Background Knowledge on the association between developmental enamel defects (DED) and early childhood caries (ECC) has importance for the drafting of prevention measures and oral healthcare planning. Aim To compare the frequency of ECC in children with and without DED and verify their association with sociodemographic factors. Design This case‐control study was carried out with Brazilian children aged one to five years. The case group made up of 98 children with ECC and the control group was made up of 98 children without ECC. DED were classified in diffuse opacity, demarcated opacity and enamel hypoplasia (Developmental Defects of Enamel Index). Sociodemographic data were collected by a questionnaire answered by parents. Statistical analysis used McNemar's test and logistic regression analyses. Results In the bivariate analysis, ECC was more frequent among children from families with poorer socioeconomic conditions (lower monthly household income P ≤ .001 and lower maternal schooling P = .001) and among those with DED (P ≤ .001). The final logistical model showed that children with DED (OR: 1.94) and a monthly household income less than two Brazilian minimum salaries (OR: 2.24) were more likely to have ECC. Conclusions The occurrence of DED and lower household income were pre‐disposing factors for the occurrence of ECC.