The investigation revealed the specific features of cell-mediated hepatocyte damage in different variants of the natural course of chronic HBV and HCV infection and in its outcomes (chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma), by determining the expression of proapoptotic (Fas, FasL) and antiapoptotic (bcl-2) factors on the surface of intralobular lymphocytes. Comparative analysis of the magnitude and pattern of cell infiltration in the liver parenchyma, the functional activity of intralobular lymphocytes showed significant differences in the above indicators in relation to the etiology and stage of the pathological process, suggesting that there were different pathogenetic mechanisms of their natural course. There was a varying potential readiness of intralobular lymphocytes for apoptosis, giving rise to different clinical manifestations in the similar morphological picture.