Objective: to evaluate the speech sound production of children diagnosed with a palatine mouth breathing and / or hypertrophic pharyngeal tonsil and compare it to that of a group of children that do not show any respiratory alterations, besides associating with age and sex. Methods: a quantitative, cross-sectional, analytical and observational research. Children from five to twelve years old have took part of the study, 50 of them diagnosed as mouth breathers (research group - RG) and 50 with no respiratory alteration (control group - CG). Anamnesis and evaluation based on MBGR protocol was performed, focusing on the speech, supported by figures and with samples of automatic and spontaneous speech. Results: there were no differences between the groups, taking into account the parents' complaint. Speech alterations, such as phonetic deflection, lingual interposition and distortions, and occlusion alterations were more frequent in RG. Speech alterations prevailed for males in 83% and the average age related to speech did not show any significance. Conclusion: mouth breathing children present more alterations of speech sounds than those presented with no respiratory alteration, regardless of the age group, being more common in male children.