Objective. To study cerebrospinal fluid and protein indices characterizing the permeability of the hematoencephalitic barrier and intrathecal immunoglobulin synthesis in children with different course and outcome of demyelinating diseases of the central nervous system. Material and methods. We examined 72 children with demyelinating diseases of the central nervous system and 16 children of a control group (without neuroinfections). Results. Differences in the concentration of myelin basic protein, immunoglobulin G, albumin and immunoglobulin indices in the cerebrospinal fluid were determined depending on acute, prolonged, chronic course of disseminated encephalitis and multiple sclerosis in children. The maximum value of the immunoglobulin index and the intrathecal immunoglobulin synthesis index was identified in multiple sclerosis. The correlations of cerebrospinal fluid indicators and protein factors in the acute period of demyelinating diseases and the formation of neurologic deficiency in the disease outcome were determined that can be used for prognostic purpose. Conclusion. The alterations in the indices obtained in this study can be included in the algorithm of laboratory examination. The results prove the involvement of various mechanisms in the pathogenesis of demyelinating diseases of the central nervous system in children.