Several factors viral genotype, mutations, vírus-host interaction, expression of viral proteins and host immune-reaction are very important in the pathogenesis of hepatotrop viral infections. Activation of Fas/Fas ligand system occurs during hepatitis which is responsible for the apoptosis of vírus infected hepatocytes. The histological features in chronic hepatitis can be classified based on the activity of near inflammatory alterations ("grade"). Stage of chronic hepatitis describes the degree of fibrosis and architectural alterations.