Inclusion Criteria:

• older than 18 years
• HBsAg+ at screening and for at least 6 months prior to study entry
• HBeAg+
• HBV DNA greater than 6 log10 copies/mL
• Platelet count greater than 50,000 platelets/mm3
• Hemoglobin greater than 7.5 g/dL
• ALT less than ULN
• Estimated creatine clearance>50 mL/min as estimated by the Crockcroft-Gault equation ((140-age) x (kg)/(serum creatine x 72) (for women x 0.85))
• Female and male participants must be practicing an effective form of contraception (male or female condom with spermicide, diaphragm or cervical cap with spermicide, intrauterine device, hormonal contraception)
• Serum alpha-fetoprotein less than 50 ng/mL within 30 days of study entry
• Childs-Pugh score less than 7 and no ascites, variceal bleeding, or hepatic encephalopathy
• able to give written informed consent and to comply with the study protocol

Exclusion Criteria:

• history or evidence of HIV, hepatitis C or hepatitis D
• known or suspected hypersensitivity to adefovir or other nucleoside/nucleotide analogs.
• history of clinically significant renal dysfunction
• any active medical or psychiatric illness that, in the opinion of the investigator, would interfere with subject treatment, assessment, or compliance with the protocol
• pregnancy or breastfeeding
• receipt of systemic corticosteroids within 90 days of study entry
• receipt of nephrotoxic drugs within 8 weeks prior to study screening or expected use of these agents during the course of the study