Correction of maxillary transverse deficiencies is a common procedure in adult patients presenting dentofacial anomalies. Nasal characteristics of these patients, as well as the effects of these procedures upon nasal patency, have not been well described yet. In the present study, measurements performed by acoustic rhinometry and frontal cephalometry in 13 patients presenting maxillary deficiencies, before and after surgically assisted maxillary expansion (SARME), were compared with those of 10 individuals with normal dentofacial characteristics and without nasal symptoms. The variables analysed were minor cross-sectional area (MCA) and nasal volume, maxillomandibular transverse index and nasal and maxillary width. The results showed a smaller transverse width and MCA in the patients as compared with normal controls. All measurements showed a tendency to increase after SARME. The nasal volumes did not differ. The nasal width showed wide variation. There was no correlation among the variables. Patients presenting maxillary transverse deficiency seem to have lower values for nasal MCA, with a tendency to increase after SARME.