Taking the etiology of malocclusion, Objective:the aim of this study was to verify the association between some malocclusion (anterior open bite, posterior cross bite and class II) and the presence of deleterious habits.Methods: The sample was comprise of 100 chindren of both genus who had been seen at Universidade Potiguar, Odontopediatricxs Clinic and who were in mixed dentition. The chindren who were selected were submited in to a clinic exame and after this avaliation was applied a questionare with the responsable to avaliet the etyological factors of malocclusion. Results:In agreement with the obtained data the percentage of the maloclusion researched were class II (64%), anterior open bite (20%), and posterior cross bite (16%). After evaliating the malocclusion with sucking habits of thong and pacifier, the thong sucking was the most common in pacients who had classII (63%) and posterior cross bite (36,4%), and the pacifier sucking was most frequent in pacients with anterior open bite (22%). Conclusion: We achieve that both habits have relevance in the development of maloclusion, where the most frequent is Class II. In realation to habts, the thong sucking was the most prejudicaial for present the most hight frequence of this sucking in patients over 4 years and producing, consequently, more injures to the dental occlusion.