Inclusion Criteria:

A patient must meet all of the following inclusion criteria to be eligible for participation in the study:

• Chronic Hepatitis B infection
• 18 through 69 years of age, inclusive
• HBV DNA >/= 1000 copies/mL

• Decompensated liver disease with all of the following:

  • CPT score of 7-12 (inclusive) OR a past history of CPT score >/= 7 and any CPT at screen </= 12
  • Serum ALT < 10 x ULN
  • Hemoglobin >/= 7.5 g/dL
  • Total WBC count >/= 1,500/mm3
  • Platelet count >/= 30,000/mm3
• Alpha-fetoprotein </= 20 ng/mL and ultrasound or other imaging with no evidence of HCC, or alpha-fetoprotein of 21-50 ng/mL and CT/MRI with no evidence of HCC, within 6 months of screening
• Calculated creatinine clearance >/= 50 mL/min
• Negative HIV, HCV and HDV serologies
• Less than 24 months of total prior adefovir dipivoxil exposure

Exclusion Criteria:

A patient who meets any of the following exclusion criteria cannot be enrolled in the study:

• Pregnant women, women who are breastfeeding or who believe they may wish to become pregnant during the course of the study
• Males and females of reproductive potential who are unwilling to use an "effective" method of contraception during the study
• Prior use of tenofovir DF or entecavir
• History of variceal bleeding, hepatorenal syndrome, Grade 3 or Grade 4 hepatic encephalopathy, or spontaneous bacterial peritonitis within 60 days of screening
• Grade 2 hepatic encephalopathy at screening
• History of solid organ or bone marrow transplant
• Current use of hepatotoxic drugs, nephrotoxic drugs, or drugs that interfere with renal tubular secretion
• Current therapy with immunomodulators (e.g., corticosteroids, IL-2, etc) or investigational drugs
• Diagnosis of proximal tubulopathy
• Use of investigational agent within 30 days prior to screening