The study is designed as a retrospective data review of medical records from participants selected from specialist secondary and tertiary care centers across the United Kingdom (UK), specializing in Hepatitis C treatment. The study is non-interventional and is designed to identify subgroups of Hepatitis C Virus (HCV) genotype 1 participants in the 'real world', including the relation between subgroup characteristics and treatment responsiveness.

Physicians will record information (from the time of first exposure to pegylated interferon alfa-2b and ribavirin) from the medical notes of participants who fit the inclusion criteria. To prevent selection bias, data are to be taken from the latest consecutive, unique participants seen by the physician over the previous 48 months. This provides a method of random sampling from a physician practice.

Inclusion Criteria:

• Participants with genotype 1 HCV infection who have been treated with pegylated interferon alfa-2b and ribavirin in the preceding 48 months will be included. They will be divided into:
• Completer participants: Patients with a diagnosis of HCV genotype 1 who have completed a course of interferon alfa-2b and ribavirin, with no prior treatment for HCV (ie, previously treatment naïve). Completer participants must have at least 24 weeks of follow up data available post completion of treatment to ensure ability to assess SVR rates.
• Early terminators: Participants who have terminated treatment early due to adverse events or other reasons (ie, exposure is incomplete).

Exclusion Criteria:

• Participants currently undergoing therapy and therefore have not terminated treatment, ie, exposure is still ongoing.
• Co-infected HCV participants (eg, human immunodeficiency virus [HIV] or hepatitis B virus [HBV]).
• Participants who received their first HCV treatment in relation to a clinical trial.

Participants with genotype 1 HCV infection who have been treated with pegylated interferon alfa-2b and ribavirin in the preceding 48 months at sites in the UK.