The content of lactoferrin (LF) was studied in the liquor and blood of patients with tick-borne encephalitis (TBE) of the meningeal and focal types; additionally, the information density of the discussed parameter was assessed for evaluating the severity and degree of the inflammation process in the central nervous system (CNS). The LF level was determined in liquor of 37 samples obtained from TBE patients (main group) and of 10 persons with osteochondrosis (controls); it was also determined in the serum taken from 21 TBE patients and from 40 healthy donors by using the immune-enzyme analysis. The LF concentration in TBE patients was found to exceed the normal value by 1.5-3 times during the whole observation period. As for the liquor, it was high, by the onset of the disease, by more than 20 times, however, after the 7th day it was higher 6-fold. A direct dependence of a concentration of the studied protein on a form and severity of the disease was established. The LF level in the liquor of TBE patients alongside with clinical signs can be an objective indicator of a severity and activity of the inflammation process in the CNS; it can also be a criteria of how much the conducted therapy effective is.