PURPOSE: to compare the hard palate dimensions in nasal and mouth breathing children of different facial typologies. METHOD: the sample comprised 54 children between seven and 11 year old, divided in two groups according to the facial type and breathing mode. The facial type was obtained through the Ricketts cephalometric analysis, and the breathing mode was determined from speech-language evaluation and otorhynolaryngologic diagnosis. In order to measure the transverse, vertical and anteroposterior length of the hard palate, plaster cast models of the children superior dental arch were obtained. To get the hard palate dimensions among the groups, parametric and nonparametric tests were used under a significance level of 5%. RESULTS: no statistically significant difference was found in hard palate measures among brachyfacial, mesofacial and dolichofacial children. A significant statistical difference in the distance among the second premolars was identified when compared with the different facial types of nasal and mouth breathing children, and such a difference was not detected in multiple comparisons. CONCLUSION: the dimensions of the hard palate did not show any difference when analyzed in different facial types regardless of the breathing mode. However, when analyzing the facial type in nasal and mouth breathers, we found a difference in the distance among the second premolars.