BACKGROUND: The narrowing of the pharyngeal space after orthognathic surgery to correct a Class III dentofacial deformity is currently of interest. The mandibular setback has been associated with a decrease in the pharyngeal airway space that is supposed to be associated with the development of obstructive sleep apnea. An association of maxillary advancement may be indicated in such cases. PURPOSE: To evaluate dimensional changes in the upper airway in patients with facial Class III deformities who have undergone combined orthognathic surgery for correction of these. METHODS: This study was developed at Taubaté University and involved the cephalometric evaluation of 20 patients with a Class III deformity who were aged between 18 and 35 years, and who were surgically treated with orthognathic surgery to achieve better facial harmony and gnathic function. The following corrective surgeries were performed: bilateral sagittal osteotomy for mandibular setback, Le Fort I osteotomy for maxillary advancement, and mentoplasty. We used 3 cephalometric measurements corresponding to the nasopharynx, oropharynx, and hypopharynx during the preoperative stage, and these were again evaluated at 3 months postoperatively. CONCLUSION: The patients who had undergone bimaxillary surgery in this study showed an anteroposterior increase in the nasopharynx and oropharynx regions and a reduction in the hypopharynx region at 3 months postoperatively. The pharyngeal airway space in patients with a Class III deformity should thus be carefully evaluated before corrective surgery. When mandibular setback is required, a combination of movements (maxillary advancement) can minimize the effects of the mandibular setback and the risk of reducing the pharyngeal airway space.