Hepatitis C virus genotype 4 (HCV-4) is spreading beyond Africa and the Middle East but data regarding treatment with pegylated interferon alpha and ribavirin of European populations infected with HCV-4 remains limited. Interestingly, European (vs. Egyptian) origin has been associated with lower sustained virological response rates. Hence the aim of this study was to investigate the treatment outcomes of Greek (vs. Egyptian), treatment-naïve patients infected with HCV-4 (subtype a) and to identify factors influencing response rates. One hundred seventy-seven consecutive patients (mean age: 44.6 ± 10.2, males: 143/177; 80.8%, Egyptians: 76/177; 42.9%) treated over a 7-year period at the Hepatology clinics of three tertiary care hospitals in Greece were retrospectively evaluated. Overall, sustained virological response was achieved in 75/177 (42.4%) of the cohort without a significant difference between the two ethnic groups [Greek: 44/101 (43.6%); Egyptian 31/76 (40.8%), P = 0.7598]. In multivariate analysis, it was found that ethnicity was not associated with an impaired response but age ≥45 years [odds ratio (OR): 0.4225, 95% confidence interval (CI): 0.2135–0.8133; P = 0.0134], diabetes (OR: 0.2346, 95% CI: 0.0816–0.0674; P = 0.0071), advanced liver fibrosis (OR: 0.3964, 95% CI: 0.1933–0.8133; P = 0.0116), and treatment suspension (OR: 0.1738, 95% CI: 0.0482–0.6262; P = 0.0075) showed an independent negative association with response to antiviral treatment. In contrast to previous European data suggesting Egyptian ethnicity to be a positive predictor for a sustained virological response, there was no influence of Greek versus Egyptian ethnicity on treatment outcomes. Higher age, advanced liver fibrosis, and diabetes have been shown to reduce significantly response rates in patients infected with HCV-4. J. Med. Virol. 84: 1217–1223, 2012. © 2012 Wiley Periodicals, Inc.