AIM:To assess sustained virological response(SVR) rates in a predominantly hepatitis C virus(HCV) genotype 4 infected population. METHODS:Between 2003-2007,240 patients who were treated for chronic hepatitis C infection at our center were included.Epidemiological data,viral genotypes,and treatment outcomes were evaluated in all treated patients.Patients with chronic renal failure, previous non-responders,and those who relapsed after previous treatment were excluded from the study.Among all patients,57%were treated with PEG-interferon(IFN)α-2a and 43%patients were treated with PEG-IFNα-2b;both groups received a standard dose of ribavirin. RESULTS:89.6%of patients completed the treatment with an overall SVR rate of 58%.The SVR rate was 54%in genotype 1,44%in genotype 2,73%in genotype 3,and 59%in genotype 4 patients.There was no statistical difference in the SVR rate between patients treated with PEG-IFNα-2a and PEG-IFNα-2b (61.5%vs 53%).Patients younger than 40 years had higher SVR rates than older patients(75%vs 51%,P =0.001).SVR was also statistically significantly higher when the HCV RNA load(pretreatment)was below 800.000(64%vs 50%,P=0.023),in patients with a body mass index(BMI)less than 28(65%vs 49%,P =0.01),and in patients who completed the treatment duration(64%vs 8%,P≤0.00001).CONCLUSION:The SVR rate in our study is higher than in previous studies.Compliance with the standard duration of treatment,higher ribavirin dose,younger age,lower BMI,and low pretreatment RNA levels were associated with a higher virological response. METHODS: Between 2003-2007, 240 patients who were treated for chronic hepatitis C infection at our center were included. Epidemiological data (AIM): To assess sustained virological response (SVR) rates in a predominantly hepatitis C virus (HCV) genotype 4 infected population. , viral genotypes, and treatment outcomes were all evaluated in all treated patients. Patients with chronic renal failure, previous non-responders, and those who relapsed after previous treatment were excluded from the study. Among all patients, 57% were treated with PEG-interferon (IFN) α-2a and 43% patients were treated with PEG-IFNα-2b; both groups received a standard dose of ribavirin. RESULTS: 89.6% of patients completed the treatment with an overall SVR rate of 58%. The SVR rate was 54% in genotype 1, 44% in genotype 2, 73% in genotype 3, and 59% in genotype 4 patients. There was no statistical difference in the SVR rate between patients treated with PEG- IFNα-2a and PEG-IFNα-2b (61.5% vs 53%). Patients younger than 40 years had higher SVR r ates than older patients (75% vs 51%, P = 0.001) .SVR was also statistically significantly higher when the HCV RNA load (pretreatment) was below 800.000 (64% vs 50%, P = 0.023), in patients with a body Mass index (BMI) less than 28 (65% vs 49%, P = 0.01), and in patients who completed the treatment duration (64% vs 8%, P≤0.00001) .CONCLUSION: The SVR rate in our study is higher than in previous studies. Compliance with the standard duration of treatment, higher ribavirin dose, younger age, lower BMI, and low pretreatment RNA levels were associated with a higher virological response.