An Observational Study of Pegasys (Peginterferon Alfa-2a) in Patients With Chronic Hepatitis B Who Have Failed Antiviral Treatment With Nucleoside (Nucleotide) Analogues

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