Aim to develop a new method of endonasal augmentation of the alveolar process of the upper jaw to reduce postoperative risks. Material and methods. The study involved 10 patients during the period of December, 2019, and June, 2021. The examination methods were: computed tomography of the nose and paranasal sinuses, upper and lower jaw, and video-endoscopy of the nasal cavity. The patients received the indonasal sinus inlay with the use of allogenic bone chips. Results. The surgical access through the lower nasal passage, under the lower nasal concha, allows to expose the maxillary sinus floor with preservation of mucous membrane integrity and to fill in the space between them with the allogenic bone material. Formation of a bone window in the lateral nasal wall using a piezotome prevents the rupture of the sinus mucous membrane. A bony fragment of the lateral nasal cavity wall transferred into the cavity of the maxillary sinus as one block with the mucosa creates additional protection for the Schneiderian membrane. Allogenic material introduced by endonasal method is substituted by the own organotypic tissue, restoring the lost volume of the maxillary sinus alveolar process. Conclusion. The endonasal method of alveolar augmentation may be used in clinical practice as an alternative to the classic methods.