Objective: To evaluate whether rapid palatal expansion (RPE) or miniscrew-assisted rapid palatal expansion (MARPE) affects nasal septum deviation (NSD). Materials and Methods: The study population includes 15 RPE patients ages 9.5 +/- 1.4 years and 15 MARPE patients ages 17.39 +/- 5.71 years with initial diagnostic cone-beam computed tomography (CBCT) scans (T0). Another CBCT scan (T1) was taken after patients underwent RPE or MARPE expansion treatment alone. NSD was evaluated three-dimensionally using a custom landmark analysis on T0 and T1 CBCT scans. Principal component analysis (PCA) and canonical variate analysis (CVA) were used to identify nasal septum shape differences before and after expansion treatment. Results: PCA and CVA showed that while there was change in nasal septum shape from T0 to T1 for MARPE and RPE treatments, the general pattern in morphological change was not found when comparing the variety of phenotypes between individuals. The Procrustes ANOVA regression found p-values for MARPE centroid size and shape were 0.75 and 1, and RPE centroid size and shape were 0.64 and 0.25, respectively, suggesting that there were no significant differences in nasal septum size and shape following expansion. CVA found p-values were 0.99 for MARPE and 1 for RPE after 10,000 permutation tests for Procrustes distances, indicating that there were no significant differences between T0 and T1 group means for both treatment groups. Conclusions: MARPE and RPE expansion treatments had no effect on nasal septum deviation from T0 to T1.