BACKGROUND: In China, hepatitis C virus (HCV) infection is characterized by an increasing prevalence during aging. This study was undertaken to evaluate the efficacy of treatment with peginterferon alpha-2a and ribavirin in elderly chronic hepatitis C (CHC) patients and study the factors related to the sustained virologic response (SVR). METHODS: The medical records of 417 patients treated with peginterferon and ribavirin were retrospectively analyzed. These patients were divided into two groups according to age: patients aged ≥65 years (n=140) and patients aged <65 years (n=277). The rate of ribavirin reduction or discontinuation and virologic response rates of the two groups were compared. The factors influencing SVR were studied by multivariate analysis. RESULTS: Ribavirin reduction or discontinuation was more frequent in patients aged ≥65 years than patients aged <65 years (37.1%, 52/140 vs 20.2%, 56/277; χ2=13.883, P<0.001). For genotype 1, patients aged ≥65 years had a higher relapse rate (50.0%, 42/84 vs 29.2%, 52/178; χ2=10.718, P=0.001) and a lower SVR rate (40.0%, 42/105 vs 60.0%, 126/210; χ2=11.250, P=0.001) than patients aged <65 years. There were no significant differences in virologic response rates between the two groups for patients with genotype 2. For genotype 1, in patients aged ≥65 years, the SVR rate of females was lower than that of males (28.6%, 12/42 vs 47.6%, 30/63; χ2=8.150, P=0.004); in the high viral load group, patients aged ≥65 years had a lower SVR rate than patients aged <65 years (30.0%, 18/60 vs 54.8%, 69/126; χ2=10.010, P=0.002). In multivariate logistic regression analysis, the independent factors associated with SVR in patients aged ≥65 years were sex (P=0.020), genotype (P=0.005), ribavirin reduction or discontinuation (P=0.009) and presence of rapid virologic response (RVR) (P=0.001). CONCLUSIONS: The rate of ribavirin reduction or discontinua-tion and relapse rate of patients aged ≥65 years with genotype 1 are high, and the SVR rate is low. Age has no impact on virologic responses rates for genotype 2. Among patients ≥65 years old, genotype 2 patients and genotype 1 patients with a low baseline viral load or achieving RVR or male may benefit from combination therapy.