Objectives: To assess the tomographic changes in the upper airway dimensions of treated patients had constricted maxilla with age range from 18 to 21 years old, using the bicortically anchored mini-screw assisted rapid palatal expansion (MARPE). Materials and methods: The current study was conducted on 24 orthodontic patients with constricted maxilla. The expander appliance consisted of two molar bands attached to maxillary first molars and 2 bi-cortically inserted mini-screws. Expansion protocol was 2 turns/day for the first week, then 1 turn/day until completion of the expansion. CBCT was performed before and 3 months after completion of the expansion. The airway volume, and linear alterations were measured to assess the changes three months after completion of the expansion. Results: There was significant increase in nasal cavity volume, nasopharynx volume, nasal cavity transverse linear dimensions, vertical linear dimensions, and maxillary width (p ˂ .05). Expanded nasal cavity and nasopharyngeal volumes correlated positively with nasal width and negatively with nasal height at ANS, and PNS planes. There were positive correlations between expanded volumes and maxillary width. Increased maxillary width correlated negatively with hard palate thickness (p ˂ .05). Conclusions: MARPE caused a significant increase in the nasal cavity and nasopharynx airway volumes. The increase in the nasal cavity and the nasopharynx volumes was correlated positively with the increase in nasal width at the ANS and PNS planes and with the increase in maxillary width. The oropharynx was not found to be changed significantly in this study.