The purpose of this clinical research study is to assess the safety and effectiveness of entecavir, as compared to lamivudine, in the treatment of adults with chronic hepatitis B infection who are hepatitis B e antigen negative.

• Male and female subjects =/> 16 years of age (or minimum age required in a given country) with history of chronic hepatitis B infection;
• HBeAg negative, anti-HBeAb positive;
• Absence of coinfection with human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis D virus (HDV);
• Absence of other forms of liver disease e.g., alcoholic, autoimmune, biliary disease;
• Less than 12 weeks prior therapy with nucleoside or nucleotide analogue antiviral agents with activity against hepatitis B (e.g., adefovir, famciclovir and lamivudine)