The following inclusion criteria were used in this study: 1) monoinfection with HCV, diagnosed by ELISA II or III, with confirmation by the qualitative determination of HCV RNA and 2) first week of antiviral treatment (either first treatment or re-treatment) for hepatitis C with pegylated interferon (PEGIFN) and ribavirin (RBV). The following exclusion criteria were also used: 1) coinfection with HBV or HIV; 2) presence of hepatic comorbidity (e.g., autoimmune hepatitis, cholestatic diseases); 3) individuals under 18 years old; and 4) refusal to participate.