Objectives: To evaluate nasal changes of monocortical versus bicortical miniscrews assisted palatal Expansion (MARPE) by Cone Beam Computed Tomography. Materials and Methods: The sample included 20 Patients (10 patients for each group) were randomly assigned to either group from the outpatient clinic of Department of Orthodontics, Faculty of Dentistry, Minia University. This prospective clinical trial formed of two groups, the 1st group was bicortical MARPE were the miniscrews used penetrated both nasal and palatal cortices and the 2nd group the miniscrews only penetrated the palatal cortex. Each patient did pre-expansion CBCT (T1) and post CBCT (T2) after expansion, time period T1 to T2 was 3 months. Soft tissue alar width, nasal height, nasal length (Sn-Pn). Skeletal pyriform height (PHT), Posterior nasal cavity width, nasal floor width and nasal septal deviation angle were evaluated. Results: The bi-cortical group was associated with significantly larger increase in AW (mean increase: 2mm vs. 1.4mm; p-value: <0.001), larger increase in PNCW (mean increase: 2.4mm vs. 1.5mm; p-value: <0.001), and larger increase in NF (median increase: 5.3mm vs. 3mm; p-value: <0.001). Additionally, the decrease in NSDA was significantly smaller in the bi-cortical group (median decrease: -1.5 °vs. -0.3°; p-value: <0.001). Conclusion: Both bi and monocortical expansions led to a significant increase in alar width and nasal floor in the short term with more increase in the bicortical group. Posterior nasal cavity width increased significantly in bicortical group. Nasal septal angle decreased significantly after expansion in bicortical group.[