aim: the aim of this study was to determine the prevalence of the anterior open bite in the complete deciduous dentition of pre-scholars children who live in the city of natal/rn, and the association of this malocclusion to possible risk factors. methods: a transverse study was performed. three hundred sixty six individuals, 5 years-old, with complete deciduous dentition were examined. anterior open bite, the dependent variable, was classified into present or absent. a number of independent variables were collected through a closed and structured questionary. these were classified into socio-economic-demographic and extrinsic factors. the extrinsic factors were breast-feeding type, time of exclusive maternal breast-feeding, time of artificial breast-feeding, presence of habit and habit duration. the determination of presence of open bite and the facial pattern (extrinsic factor) was done through clinical exams. the association between the anterior open bite and the independent variables was analysed through chi-square tests with a significance value of 5%. results and conclusions: significant association was found between the economic class, family income and the presence of habits. the prevalence of the anterior open bite was 20.6%.