PURPOSE: to investigate the relationship between oral breathing of different etiologies and persisting non-nutritive sucking habits in establishing structural alterations in the stomatognathic system. METHOD: the sample comprised 78 children between 7 and 11 year old, 36 boys and 42 girls, divided in two groups based on non-nutritive sucking habits and breathing mode. All children underwent otolaryngological, speech-language and dentistry evaluations. Data analysis was performed using Chi-square test considering significance level of 5%. RESULTS: there was significant association between breathing mode and lips posture; between breathing mode and hard palate; between nonnutritive sucking habits and cheek posture. In the analysis of the association between breathing mode and nonnutritive sucking habits with the habitual lips posture and hard palate, we also forund a statistical significance. CONCLUSION: it was found that the altered lips posture and hard palate was more frequent in the vicious and obstructive mouth breathers groups. The asymmetrical cheeks posture was more frequent among children with habits. The altered lips posture and hard palate alterations were also more frequent in oral breathers regardless of the presence or absence of any habits.