OBJECTIVE: To verify the presence of voice disorder and the stomatognathic system in an oral breathing child. CASE REPORT: A female patient, 11:7 years old, diagnosed with speech mouth breathing, evaluated in clinical school with prior consent of the guardians through the Term of Consent of the research. In the interview, referred to prolonged oral habits, bruxism, difficulty in chewing food consistent, nocturnal drooling, snoring, allergic reactions and complaints of hoarseness. In the evaluation of the stomatognathic system, hypotension has been observed on the lips, tongue and cheeks, malocclusion, unilateral chewing on the right, adapted swallowing due to poor occlusion and hypotension lingual and lateral lisp. The analysis was performed perceptive auditive vocal on the issue of numbers one through twenty months of the year and days of week and naming, verifying type of voice slightly hoarse and breathy hypo nasal and moderately; focus resonance laryngeal moderately and discreetly hypo nasal, moderately severe pitch, loudness, intonation and modulation of appropriate loudness CONCLUSION: The children studied showed moderate alterations of the stomatognathic system and dysphonia mild-moderate probably due to the breathing mode that generates changes in oral structures and oral functions, as well as in phonation . The presence of hoarseness and breathiness (acoustic noise) contribute to the low pitch and laryngeal resonance is possibly associated with absence of nasal functions (heating, humidification, and filtration) on the inhaled air passing through the vocal cords, which also justifies the hyponasality.