Objective: To investigate the effect of hard palate angulation caused by septal deviation on the volume ofthe maxillary sinus.Methods: Coronal computed tomographic (CT)scans of 1568 patients aged from 18 to 60 were examined. CT scans of 402 patients were included in thestudy. On these scans, the maxillary sinus volume, theangle of the nasal septal deviation, and the angulationof the hard palate were calculated using the ImageJsoftware. Each maxillary sinus volume was statistically compared with each other and with those in thecontrol group. Correlations between palatal angulation and septal deviation were determined.Results: Deviated nasal septum whether with orwithout deflection of the hard palate was noted tohave caused changes in the volume of the maxillarysinus in both female and male patients. The volumeof the maxillary sinus on the deviated side was lessthan that of the opposite side, and the differences between the volumes of both sinuses were statisticallysignificant (p<0.05). No significant differences werenoted when compared with the control group. A positive correlation was observed between the nasal septaldeviation angle and the angulation of the hard palate.Conclusion: Regardless of whether or not it affectsthe hard palate, nasal septal deviation reduces the volume of the maxillary sinus on the deviated side butdoes not affect the total volume of the maxillary sinuses. Significant differences between the volumes onthe two sides can lead to facial asymmetry.