The invention concerns the use of alisporivir (= Debio-025 or DEB025) in the treatment of Hepatitis C virus infection genotype 1 infected African American patient. Alisporivir is to be administered in an amount of about 400 to about 600 mg twice per day, preferably in combination with other antiviral agents. In a preferred embodiment, the following dosage regimen is administered : pegylated interferon alfa 2a (PEGASYS) at a dose of 180 ug subcutaneously once weekly for 24 or 48 weeks in combination with ribavirin (RBV or COPEGUS) administered in an oral dosage of 800/1200 mg daily (weight based) for 24 or 48 weeks and 400 mg alisporivir (DEB025) orally twice daily for 24 or 48 weeks.