Maxillary sinus (MS) cysts are benign formations that are often an accidental finding during X-ray examinations. The most informative methods are CT and MRI. Cysts usually look like round or domeshaped formations, most often localized in the lower part of the MS. Medical records of 86 patients  (51 men and 35 women) with MS cysts were analyzed; the age of the patients ranged from 18 to 83 years. It was found that in the presence of an MS cyst, only 66.3 % of patients had rhinological complaints (the most common complaint was nasal breathing difficulty- 54.6 %), in 33.7 % of patients, MS cysts were an accidental finding. Most often, MS cysts were located on the lower wall of the  MS (74 %), had an average volume of 2.1 cm3 and occupied less than half of the sinus volume in 74 % of cases. Sinusitis (53.5 %) and deviated nasal septum (66.3 %) may play a certain role in the development of maxillary sinus cysts. More than half of the patients (53.5 %), along with the cyst, had signs of hyperplasia of the mucous membrane on other walls of the maxillary sinus (according to CT data). No reliable connection between the presence of maxillary sinus cysts and allergies has been established.