The hepatitis C virus (HCV) genotype is an important predictive outcome parameter for pegylated interferon plus ribavirin therapy. Most published therapeutic trials to date have enrolled mainly patients with HCV genotypes 1, 2 and 3. Limited studies have focused on genotype 4 patients, who have had a poor representation in pivotal trials. Our aim was to evaluate the efficacy and safety of treatment with standard dose pegylated interferon alfa-2a in combination with weight-based ribavirin in patients with chronic hepatitis C genotype 4. In this prospective observational study, 198 patients with HCV-4 were included in this study from February 2004 to August 2005,188 patients who received at least 1 dose of drugs were included in the ITT analysis and they were treated with pegylated interferon alfa-2a and ribavirin for 48 weeks. Baseline and demographic characteristics, response to treatment at weeks 12, 48 and 72, and the nature and frequency of adverse effects were analyzed. Virological response at week 12 was achieved in 144 patients (76.6%). Virological response at the end of treatment was present in 110 patients (58.5%). At week 72, 99 patients presented SVR (52.7%). The reported adverse events were similar to those found in the literature for treatments of similar dose and duration. In conclusion, combined treatment with pegylated interferon alfa-2a and ribavirin was well tolerated and effective in chronic hepatitis C genotype 4, yielding response rates between those reported for genotype 1 and those of genotypes 2-3.