We assess the efficacy of pegylated interferon (peg-IFN) with ribavirin (RBV) and the predictors of sustained virological response (SVR) among HIV/hepatitis C virus genotype 4 (HCV-4)-coinfected patients. Thirty-nine (31.5%) of 124 individuals with HCV-4 achieved SVR compared with 103 (22.7%) of 453 individuals with HCV genotype 1 (P=0.046). Only interleukin-28B (IL28B) genotype CC was independently associated with SVR in HIV/HCV-4-coinfected patients. The efficacy of peg-IFN with RBV in coinfected individuals with genotype 4 is significantly higher than in those with genotype 1. IL28B CC genotype is the main predictor of response in this population.