The aim of the study was to investigate the relationship between nasal septal deviation and the middle turbinate hypertrophy using computed tomography. In this retrospective analysis, we examined 77 patients with nasal septal deviation. The mucosal and bone structures of the middle turbinate and the angle of the septum were measured using radiological analysis. Measurements of the middle turbinate on the convex side were compared to those on the concave side. Measurements of the bony and mucosal structure area of the middle turbinate were significantly greater than those on the concave side. The dimensions of medial mucosa thickness and bone thickness were not significantly different between the convex and concave sides. No significant correlation was found between the angle of deviation and other parameters. The present findings suggest that compensatory middle turbinate hypertrophy was caused both by conchal bone growth and mucosal hypertrophy in patients with nasal septal deviation.