Timely recognition and rational therapy of hearing loss in inflammatory middle ear diseases is one of the most important tasks of modern otorhinolaryngology. Purulent inflammations of the middle ear, both acute and chronic, are still one of the most common ENT diseases and in the structure of pathology of ENT organs account for 5.1 to 58% of cases, and from 8.6 to 37% of cases cause a degree of hearing loss.The etiology, pathogenesis, modern methods of diagnostics and treatment of patients with chronic inflammatory middle ear diseases are analyzed in the monograph, the algorithm of diagnostics and treatment of chronic inflammatory middle ear diseases is worked out and recommendations for physicians are given.This monograph is intended for masters of otorhinolaryngology, clinical residents and doctors of otorhinolaryngology.