BACKGROUND: Hepatitis C virus (HCV) genotype 4 is a common infection in Egypt and is the leading cause of liver disease.OBJECTIVE: To study the efficacy and safety of a novel 20 kD pegylated interferon alpha-2a derived from Hansenula polymorpha in combination with ribavirin for the treatment of Egyptian patients with genotype 4 chronic hepatitis C (CHC).METHODS: One hundred seven patients with genotype 4 CHC were involved in the present study. Liver biopsy was performed in all patients. All patients received a fixed weekly dose of 160 μg of a novel pegylated interferon in combination with ribavirin in standard and adjusted doses. Serum HCV RNA levels were assessed by a real-time sensitive polymerase chain reaction assay at four, 12, 48 and 72 weeks after the start of therapy. Patients demonstrating an early virological response (EVR) completed a 48-week course of treatment.RESULTS: The overall sustained virological response (SVR) was 60.7%. The SVR in patients with a rapid virological response was significantly higher (91.7%) than in patients with complete EVR (67.74%) (P=0.033) and partial EVR (56.14%) (P=0.003). SVR was also significantly higher in patients with a low degree of liver fibrosis according to Metavir score (F1 and F2) (67.57%) compared with those with a high degree of liver fibrosis (F3 and F4) (45.45%) (P=0.017). The baseline viral load had no impact on SVR in the present series nor were any serious adverse events reported.CONCLUSION: The novel pegylated interferon alpha-2a assessed in the present study was effective for the treatment of patients with genotype 4 CHC, and was safe and well tolerated.