The objectives of this study are to evaluate the occurrence of postoperative middle turbinate lateralization and the relationship between this lateralization and the risk of iatrogenic sinusitis after endoscopic transnasal sphenoidotomy procedure. Patients who undergone endoscopic transnasal sphenoidotomy and came under the surveillance of our otorhinolaryngology department between the January of 2010 and the December of 2015 were retrospectively scanned. Among them, the patients who were evaluated with paranasal sinus computed tomography (CT) postoperatively were included in the study. The amount of middle turbinate lateralization in each patient was evaluated by comparing their routine preoperative CT image with the postoperative CT image. The air-fluid levels or soft tissue opacifications in the sinuses or obstruction of the ostiomeatal complex were accepted as the evidence of sinusitis on the images. The patients were asked questions regarding their symptoms of sinusitis on a phone interview for the statistical evaluation of their preoperative and postoperative Visual Analog Scale scores of complaints of sinusitis. The difference between preoperative and postoperative measurements was found to be statistically significant (p < 0.001, 95% CI). The middle turbinate position was lateralized in 31 patients (81.6%), medialized in four patients (10.5%), and remained unchanged in three patients (7.9%). Overall, the sinus opacification and mucosal thickening rates did not change significantly which suggested the operation did not pose patients at increased risk of sinusitis. Mean VAS scores of complaints of sinusitis did not change significantly except for sensation of facial pressure, which showed a minor but statistically significant decrease (p < 0.001). This study revealed the lateralization of the middle turbinate after transnasal sphenoidotomy. However, it seemed that this lateralization did not create a predisposing factor for the development of acute and chronic sinusitis.