V.N. Krasnozhen Kazan State Medical Academy Kazan, Russia Performing endoscopic operations on the paranasal sinuses and observing mucociliary transport, it was necessary to note that the secretion transport pathway in the sphenoid sinus has its own characteristics. The aim of the study was to clarify the secretion transport pathway in the sphenoid sinus (using blood dissolved in the secretion as the most physiological marker). Material and methods. The study included 32 patients with sinusitis aged 23 to 65 years. Of these, 18 were men and 14 were women. The disease duration ranged from 6 months to 5 years. Diagnostic endoscopy revealed the presence of various pathologies leading to obstruction of the nose, the ostiomeatal complex, and the area of ????the natural anastomoses of the maxillary and sphenoid sinuses. The nature of the identified pathology was varied - polyps, cysts, thickening of the mucous membrane, etc. CT allowed us to judge the integrity of bone structures, the presence of bone septa or spurs in the sinuses and the state of natural anastomoses, the nature of pathological formations based on determining their optical density. When comparing the results of endoscopic operations on the paranasal sinuses with preoperative computed tomography data, the accuracy of the diagnosis made before the operation was revealed in 86% of patients. Based on the analysis of CT and sinusoscopy data, the following pathological changes were detected: - unilateral polypous ethmoidomaxillary sphenoiditis - 6 patients (18.7%); - bilateral polypous ethmoidomaxillary sphenoiditis - 6 patients (81.3%); — curvature of the nasal septum with respiratory failure - 6 patients (18.7%), Extreme deviations of the intersinusal septum in the sphenoid sinus were observed in 34.3% of cases (11 patients), S-shaped curvature in 18.8% of cases (6 patients), the septum was located almost along the midline in 46.9% of cases (15 patients). Consequently, symmetry of the right and left halves of the sphenoid sinuses was found in almost half of the patients. Of the 32 patients who underwent endoscopic surgery, it was possible to observe and video document the pathway of secretion movement: 1. in the sphenoid sinuses in 6 patients, of which 4 had a bilateral process and 2 - unilateral; 2. in the maxillary sinuses - in 6 patients with bilateral isolated cystic sinusitis; 3. In 20 patients with bilateral polypous sinusitis, including unilateral cystic sinusitis in 5. Consequently, a bilateral examination was performed on 4 sphenoid sinuses (8 symmetrical halves of the sinuses) and 12 maxillary sinuses. The secretion transport pathway in the sphenoid sinus is directed inward—to the posterior and lateral walls. The secretion then moves to the superior wall and toward the superior aspect of the sinus ostium, then divides, descends along the lateral margins of the ostium, and is evacuated from the sinus primarily in the area of ??the inferior margin of the ostium. Thus, the inferior margin of the natural ostium is the key area of ??sphenoid sinus clearance, which should be taken into account when performing functional endoscopic surgery.