A Study of Pegasys (Peginterferon Alfa 2a) Alone or in Combination With Tenofovir in Patients With Chronic Hepatitis D.

Inclusion Criteria: * adult patients, \>/=18 years of age * chronic hepatitis D * positive for HBsAg \>/=6 months, for anti-HDV \>/=3 months and for HDV-RNA at screening * negative pregnancy test; fertile males and women of childbearing age should use two reliable forms of contraception throughout study Exclusion Criteria: * antiviral therapy for chronic hepatitis D within the previous 6 months * previous therapy with pegylated interferon alfa * treatment with conventional interferon alfa for \>12 months * hepatitis A or C, or HIV infection * decompensated liver disease (Childs B-C) * history or evidence of medical condition associated with chronic liver disease