The antiviral treatment of chronic hepatitis B by interferons was significantly extended in last decade by synthetic nucleosides and nucleotides which are given perorally. Lamivudin (100 mg/day) was the first, adefovir dipivoxil (10 mg/dax) was the second drug, and nowadays extensive clinical trials are continuing with entecavir (0.5 mg/day) which is an analogue of guanosine with high and selective antiviral activity against hepatitis B virus. It is given to HBeAg positive and negative patients with chronic hepatitis B and serological markers of viral replication. In comparison of entecavir to lamivudine treatment there was significantly higher histological, virological and biochemical improvement in entecavir. Safety and tolerance profil was similar in both drugs and no antiviral resistence to hepatitis B virus was meanwhile observed during 12 moths entecavir treatment.

        Key words: chronic hepatitis B, antiviral treatment, entecavir.