We investigated the efficacy of peginterferon alfa-2a plus ribavirin (α-2a therapy) for chronic hepatitis C patients who relapsed or did not respond to peginterferon alfa-2b plus ribavirin (α-2b therapy). Eleven patients with relapse and 5 non-responders to α-2b therapy received α-2a therapy for 48 to 72 weeks. In those with relapse, the rate of RVR, complete EVR and SVR were 54.5%, 72.7% and 72.7%, respectively. In non-responders, the rate of RVR, complete EVR and SVR were all 0%. Three of 5 LVR patients on α-2b therapy achieved SVR on α-2a therapy. Our findings suggest that patients showing relapse on α-2b therapy could achieve an early viral response and high SVR rate on α-2a therapy, non-responders could not.