Vitamin D deficiency is commonly found in patients with chronic hepatitis C. The investigators hypothesize that the correction of hypovitaminosis D before the initiation of anti-HCV combination therapy and the maintenance of an optimal vitamin D status during antiviral therapy could improve the antiviral efficacy

An open-label, prospective evaluation of the efficacy of vitamin D supplementation starting 1 month before and continuing for the duration of combination therapy with pegylated interferon alpha (2a or 2b) plus ribavirin in patients with chronic viral hepatitis C genotype 1 or 4, nonresponders to a first antiviral therapy.Vitamin D supplementation is started one month before antiviral therapy in order to introduce pegylated interferon plus ribavirin in patients with optimal vitamin D status

Inclusion Criteria:

• Chronic Hepatitis C Genotype 1 or 4
• Hypovitaminosis D defined by a value <30 ng / ml
• Patient non responder to previous antiviral combination therapy of Pegylated Interferon and Ribavirin defined by a decrease in viral load <2 log at week 12 of the first course (Peg/RBV)
• Patient who received at least 80% of the optimal dose of Pegylated Interferon and Ribavirin according to current recommendations
• Patient for which the investigating physician decided to initiate treatment for hepatitis C combination therapy

Exclusion Criteria:

• Decompensated liver disease: Child-Pugh B> 8 or one of the following criteria: bilirubin> 35 micromol/L, TP <50%, ascites, recurrent encephalopathy
• Positive serology for HBV and HIV
• Alcohol consumption exceeding 50 g/day
• Chronic intake of vitamin D
• Thrombocytopenia <50 000/mm ³, neutropenia <750/mm ³, hemoglobin <11 g/dL
• Pregnant women