The combined therapy with interferon alfa plus ribavirin (INF+RBV) is considered the most appropriate treatment for patients with chronic hepatitis C virus genotypes 2 and 3 in Brazil. However, wide variations in the rates of sustained viral response (SVR) have been reported among such patients. We evaluated, retrospectively, factors associated with SVR in subjects with chronic hepatitis C virus genotypes 2 and 3 and that received medication from the Health Secretariat of the state of São Paulo. One-hundred-seventy-seven consecutive patients with chronic hepatitis C were treated for 24 or 48 weeks according to the viral genotype. Patients co-infected with associated hepatic diseases or who had problems with alcohol abuse were excluded. The genotype of the HCV-RNA was identified through restriction analysis, the viral load through quantitative PCR (Amplicor, Roche) and the degree of hepatic fibrosis according to the Metavir score. Demographic, virological and histological parameters were submitted to binary logistic regression analysis to identify the variables associated with SVR. The overall rate of SVR was 36.4% for the 177 patients, and genotype 2 or 3 was the main parameter independently associated with SVR. Among the 77 patients with these viral genotypes, only the stage of fibrosis had a significant effect on the SVR (odds ratio (OR) = 3.035; 95% CI (confidence interval) = 1.196-7.699; p=0.019). The rate of SVR among the subjects with fibrosis at an advanced stage (F3-F4) was 38%, compared to 75% for patients with fibrosis at an initial stage (F0-F2). Consequently, other therapeutic options should be considered for patients with genotypes 2 and 3 who have advanced fibrosis.