Objective:To investigate the effect of septal deviation severity on the dimensions of the lateral lamina of the cribriform plate (LLCP), middle turbinate length (MTL), and the angle of the lateral lamella of the cribriform plate (ALLCP).Methods:Paranasal computed tomography (CT) scans of 148 patients with septum deviation (102 males, 46 females; age range 18-63 years) were retrospectively evaluated. The patients were divided into 3 groups according to the measured angle of nasal septal deviation as mild (<9 degrees), moderate (9-15 degrees), or severe (>15 degrees). Height and width of LLCP, MTL, and ALLCP on both sides were measured and these parameters were compared between the groups according to the septal deviation side.Results:The nasal septum was deviated to the right in 73 patients (49.3%) and to the left in 75 patients (50.7%). The LLCP dimensions, MTL, and ALLCP between the groups at the contralateral side were not statistically different (P>0.05). The LLCP height, ALLCP between the groups at the ipsilateral side were not statistically different (P>0.05). There was a significant difference in the LLCP width at the ipsilateral side between the groups (P=0.039). The MTL at the ipsilateral side was significantly different between the groups (P=0.003).Conclusion:The severity of nasal septum deviation in patients with nasal septum deviation affects the ipsilateral LLCP width and the ipsilateral MTL. These findings suggest that the increase in the severity of septum deviation in patients undergoing endoscopic sinus surgery does not increase the risk of possible damages that may occur in LLCP.