The generalized interdental spacing of the anterior segment is the most common characteristic in deciduous dentition and is accepted by some researchers as favorable to the alignment of the anterior permanent teeth; in addition, when it comes to anterior interdental spacing in deciduous dentition, another variable should be investigated: the recording of sucking habits;Thus, the purpose of the present study was to evaluate the prevalence of anterior interdental spacing characteristics in the deciduous dentition in Japanese-Brazilians and Brazilian leucoderms, as well as to test the association between the occlusal variables surveyed and non-nutritive sucking habits.