Study of the pathogenesis of viral hepatitis C is of primary importance because of persistence of this virus and high incidence of chronic course of this disease, and as a consequence, development of cirrhotic and neoplastic processes in the liver determining high mortality from this condition. Proinflammatory cytokines, in particular, tumor necrosis factor, play an important role in the development of these pathological processes. The content of tumor necrosis factor in the circulating blood plasma and hepatocytes increases in acute and chronic hepatitis C. It seems that the capacity of cells to produce proinflammatory IL in high or low levels spontaneously or after antigenic stimulation largely determines the outcome of infectious process in contact with the virus.