Pathological ventilation of the maxillary sinus (MS) is one of the risk factors for the formation of chronic maxillary sinusitis.PURPOSE OF STUDY: Is to evaluate the effectiveness of the method of restoring the medial wall of the MS with an autograft - a quadrangular cartilage of the nasal septum using the butterfly technique (Patent Application No. 2018140468, priority of 11/19/2018).MATERIAL AND METHODS: The study included patients who underwent septoplasty, endoscopic surgery on the MS with plasty of the medial wall of the MS (1st, main group, n=136), as well as patients who underwent surgery according to Caldwell-Luc with the formation of persistent nasoantral anastomosis in the lower nasal passage (2nd, control group, n=56). The criteria for the inclusion of patients in the study were as follows: the presence of MS fungal body; inverted papilloma with lesions of the MS; cysts and/or a foreign body of the MS with localization in the alveolar bay without involving the natural anastomosis in the pathological process; concomitant 3rd or 4th, or 5th or 6th types of curvature of the nasal septum according to R. Mladina (1987). An objective assessment of the condition of the patients was carried out using the SNOT-22 clinical questionnaire, and for analysis the state of aerodynamics of the nasal cavity and MS in patients of various groups after surgical treatment used the method of computational aerodynamics.RESULTS: In patients with nasoantral ostium in the lower nasal meatus, the pathological maxillary sinus aeration one was observed. It is recommended to close the nasoantral ostium to prevent violations of the aerodynamics of the nasal cavity and the maxillary sinus during surgery through the lower nasal meatus.CONCLUSION: Our proposed method for closing a defect in the lower nasal passage is effective. The autograft is well established, contributes to the speedy restoration of normal sinus aerodynamics.