In this work, the subjectwere the indices of the immune status of the patients. The content of various subpopulations of T lymphocytes in the meningeal form of tick-borne encephalitis was studied. The aim of the study was to assess the role of various subpopulations of T lymphocytes in the immunopathogenesis of the meningeal form of tick-borne encephalitis. Various studies were performed, which made it possible to identify the nature of changes in immunological processes in the course of the pathological process.