For the first time on the territory of Primorsky region the authors carried out the analysis of sickness rate and clinical course of tick-borne encephalitis of children. Most of the diseased were children from 4 to 12 years. The infection had occurred not only because of tick sting but also after using goat or cow-s milk. At 50.7% of morbid events the disease proceeded as febrilily, at 18% – in the meningeal form and at the remaining ones as focal variants of encephalitis. Under medium-serious forms, in contrast to the serious ones, the disease was characterized by faster normalization of body temperature and reduction of neurologic symptomatology.