OBJECTIVE: To describe the association between oral habits, breastfeeding and malocclusion in children of three years old to five years old. METHODS: cross-sectional study, observational, conducted with 41 children through a questionnaire about breastfeeding habits and oral and dental examination for the evaluation of occlusion. For comparisons between groups we used Fisher's exact test or chi-square, depending on the variable. The significance level was 5%. RESULTS: 92.7% of children were breast-fed mothers (mean 16.8 + 13.2 months), however only 5% exclusively for more than 6 months (mean 3 + 2 months). Among the oral habits, the incident was over a bottle (100%), followed by sucking a pacifier (56%). The low-income families breastfed longer (p = 0.017) and offered less bottle (p = 0.05). Children defined in the habit of keeping his mouth open sucking habits had more (p = 0.031, p <0.001). In relation to occlusal changes, 48.8% showed abnormalities, the most prevalent anterior open bite (45%), followed by overbite and crossbite. A correlation of occlusal alteration with the use of a pacifier (p = 0.008), and the habit of staying with his mouth open (p = 0.014). CONCLUSIONS: Given the high prevalence of oral habits and changes in occlusion in children, considering the magnitude of its possible consequences and the difficulty of intervention after installing them, is of great importance for studies in the area.