This is an open study to evaluate the efficacy, safety of clevudine monotherapy or adefovir and clevudine combination in patients with chronic hepatitis B.

Inclusion Criteria:

• Patient is 18 years and older.
• Patient is documented to be HBsAg positive for > 6 months.
• Patient is HBV DNA positive with DNA levels ≥ 1×10^5 copies/mL within 30days of baseline.
• Patient has ALT levels ≥ 1×ULN
• Patient who is able to give written informed consent prior to study start and to comply with the study requirements.

Exclusion Criteria:

• Patient is currently receiving antiviral, immunomodulatory, cytotoxic or corticosteroid therapy.
• Patients previously treated with interferon, peg-interferon or other immunomodulatory within the previous 6 months.
• Patients previously treated with clevudine, lamivudine, adefovir, entecavir, telbivudine, Tenofovir or any other investigational nucleoside for HBV infection.
• Patient with clinical evidence of decompensated liver disease (Total bilirubin < 2.0mg/dL, Prothrombin time < 1.7(INR), Serum albumin≥3.5g/dL)
• Patient is coinfected with HCV, HDV or HIV.
• Patient has a history of ascites, variceal hemorrhage or hepatic encephalopathy.
• Patient with clinical evidence of hepatocellular carcinoma
• Patient with previous liver transplantation
• Patient is pregnant or breast-feeding.
• Patient has a clinically relevant history of abuse of alcohol or drugs.
• Patient has a significant immunocompromised, gastrointestinal, renal,
• hematological, psychiatric, bronchopulmonary, biliary diseases excluding asymptomatic GB stone, neurological, cardiac, oncologic(except HCC)or allergic disease or medical illness that in the investigator's opinion might interfere with therapy.
• Patient has creatinine clearance less than 60mL/min as estimated by the following formula: (140-age in years) (body weight [kg])/(72) (serum creatinine [mg/dL]) [Note: multiply estimates by 0.85 for women]