The aim of this study was to evaluate the two-dimensional (2D) and three-dimensional (3D) changes in the pharyngeal airway space (PAS) in 20 class III patients who underwent mono- or bimaxillary surgery using cone-beam computed tomography (CBCT). CBCT examination was obtained before surgery (T1) and at least 3 months after surgery (T2). The pharyngeal airway of each patient was studied at three levels: the level of the posterior nasal spine, the level of the most inferior point of the soft palate, and the level of the top of the epiglottis. At each of these levels, the anteroposterior and lateral dimension as well as cross-sectional area were measured. The volume of the whole PAS and volume between each cross section were also measured. The area and anteroposterior dimensions at the level of the most inferior point of the soft palate significantly decreased in patients who underwent monomaxillary surgery. The volume of the PAS decreased in both groups, but decreased significantly only in the monomaxillary group. The upper volume decreased in the mono- and increased in the bimaxillary group. The lower volume significantly decreased in the monomaxillary group. However, results showed that PAS decreased more after mono-than after bimaxillary surgery.