Programmed cell death of lymphocytes in patients with chronic infections induced by tick-borne encephalitis, hepatites B and C was investigated. The injury character in realization of lymphocyte apoptosis is shown to depend on molecular features of the infectious agent. Apoptotic death of lymphocytes was elevated after their incubation in vitro with dexamethazone, etopozide and in the environment without serum. Receptor-dependent and mitochondrial paths of apoptotic signal conduction ways are preferably modulated in chronic virus persistence.