Intermediate uveitis is among most severe forms of endogenous uveitis which is more common in young people, being characterized by minimal clinical manifestations at early stages of the disorder. A significant and, sometimes, irreversible decrease in visual acuity is associated with development of long-term complications of chronic cintermediate uveitis (CIU), i.e., complicating cataracts (in up to 57% of the cases), cystic maular edema developing at a frequency of up to 31%), as well as ophthalmic hypertension and glaucoma (up to 16% of the patients). The incidence rate of CIU is 1.5 per 100,000 per year. The eye, despite its high immune privilege, is susceptible to infectious and inflammatory diseases. Clinical and histopathological data suggest autoimmune origin of CIU associated with possible response to some endogenous antigen of unknown origin. The main effectors of inflammation in peripheral chorioretinal structures are CD4+T lymphocytes, which are found in paravasal infiltrates and vitreoretinal exudates in CIU. An important role in CIU pathogenesis is attributed to IL-6 and IL-8, TNFá, vascular endothelial growth factor (VEGF), and micro-RNAs, which show increased expression in most CIU patients. Impaired state of intestinal bacterial microbiome is a potential trigger of intraocular inflammation. Genetic predisposition for CIU was also revealed, due to polymorphisms of human leukocyte antigens and some other genes. It is necessary to expand and deepen our knowledge on the disease pathogenesis, in order to develop effective pharmacological treatment of CIU. The article is review of literature discussing the modern scientific ideas concerning etiology and mechanisms of the CIU development.