This observational study will evaluate the efficacy and safety of Pegasys (peginterferon alfa-2a) in patients with chronic hepatitis B who have failed antiviral treatment with nucleoside (nucleotide) analogues. Data will be collected from patients treated according to the current Summary of Product Characteristics and local standard of care and regulations during 48 weeks of treatment and 24 weeks of follow-up.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Positive HBsAg for more than 6 months before assignment to treatment with Pegasys
• Detectable HBV DNA (as measured by PCR)
• HBeAg positive and negative patients
• Patients previously treated with nucleoside (nucleotide) analogues who have failed antiviral treatment and have been assigned to treatment with Pegasys according to the local therapeutic standard
• Elevated serum alanine aminotransferase (ALT)
• Chronic hepatitis B confirmed by liver biopsy or non-invasive assessment (FibroScan), ARFI, FibroTest) or by clinical evaluation

Exclusion Criteria:

• Contraindications to treatment with Pegasys according to the Summary of Product Characteristics
• Hepatocellular carcinoma and/or severe hepatic dysfunction or decompensated cirrhosis of the liver
• Immunosuppression, immunomodulatory or chemotherapy within the last 6 months prior to start of Pegasys treatment
• Planned other than Pegasys antiviral treatment during Pegasys therapy
• Chronic liver disease other than chronic hepatitis B
• Pregnant or breast-feeding women
• Inadequate hematologic function
• Autoimmunology disorders
• Co-infection with chronic hepatitis C or HIV

Patients with chronic hepatitis B initiated on therapy with Pegasys