Suppressing effect of tick-borne encephalitis (TBE) virus on expression of lymphocyte subpopulation receptors has been demonstrated in vitro. Effects of 14 immunomodulators on expression of T lymphocyte receptors under the effect of TBE virus have been compared. Anti-TBE immunoglobulin, 4-iodantipyrin, and leukinferon had the highest protective effect after a preventive injection. Thymalin and leukinferon in combination with human leukocytic interferon were the most effective within the treatment protocols. Further studies of sensitivity of immunoregulator cells to immunomodulators is recommended with the aim of adding these drugs to therapy of TBE patients.