As of July 31, 2009, the recruitment for Black/African Americans was completed.

Inclusion Criteria:

• Chronic HBV infection, with either HBeAg-positive (HBeAb-negative) or HBeAg-negative (HBeAb-positive) disease
• Black/African American Race and/or Hispanic ethnicity (As of July 31, 2009, the recruitment for Black/African Americans was completed)
• Nucleoside/tide-naive
• Males or females ≥ 16 years of age (or minimum age required in a given country)
• Compensated liver function
• HBV DNA HBe-negative > 10^4 copies/mL HBe-positive > 10^5 copies/mL
• ALT of 1.3 to 10 x ULN
• No Co-infection with HIV, HCV or HDV

Exclusion Criteria

• WOCBP who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period and for up to 6 weeks after study medication has been discontinued
• Women who are pregnant or breastfeeding
• Women with a positive pregnancy test on enrollment or prior to study drug administration
• Evidence of decompensated cirrhosis including but not limited to: variceal bleeding; hepatic encephalopathy; or ascites requiring management with diuretics or paracentesis
• Coinfection with human immunodeficiency virus (HIV), hepatitis C virus (HCV; coinfection is defined as HCV Ab positive with detectable HCV ribonucleic acid [RNA] by PCR) or hepatitis D virus (HDV)
• Recent history of pancreatitis (resolution of any recent pancreatitis must be documented by normal lipase at least 12 weeks prior to the first dose of study medication)
• Currently abusing illegal drugs or alcohol sufficient, in the investigator's opinion, to prevent adequate compliance with study therapy or to increase the risk of hepatotoxicity or pancreatitis
• Other serious medical conditions that might preclude completion of this study or that require chronic administration of prohibited medications
• Serum creatinine > 1.5 mg/dL
• Hemoglobin < 10.0 g/dL
• Platelet count < 70,000/mm3
• Absolute neutrophil count < 1200 cells/mm3
• Serum alpha fetoprotein (AFP) level > 100 ng/mL. If the AFP level is between 21 and 100 ng/mL, it must be repeated. If the repeat AFP level is between 21 and 100 ng/mL and if ultrasonography or computerized tomography (CT) of the liver performed prior to the first dose of study medication does not demonstrate a focal lesion suggestive of carcinoma, the subject may be dosed in the study
• Known history of allergy to nucleoside analogues
• Any prior therapy with Entecavir
• Any prior or concomitant use of nucleoside or nucleotide analogue antiviral agents with activity against hepatitis B (e.g., ETV, LVD, ADV, tenofovir [TDF], emtricitabine (FTC), clevudine, telbivudine [LdT], famciclovir), or any other experimental anti-HBV antiviral agent
• Therapy with interferon, thymosin alpha or other immunostimulators within 24 weeks of enrollment (i.e., dosing) into this study
• Subjects who require chronic administration of concomitant medications which cause immunosuppression or which are associated with a high rate of nephrotoxicity or hepatotoxicity, or which affect renal excretion, should not be enrolled in this study
• Unable to tolerate oral medication
• Poor peripheral venous access
• Prisoners or subjects who are compulsorily detained (involuntarily incarcerated) for treatment of either a psychiatric or physical (e.g., infectious disease) illness must not be enrolled into this study