['Treatment options for hepatitis C have developed rapidly in the past decade. The current treatment of choice is a combination of pegylated-interferon-alpha (PEG-IFN-alpha) and ribavirin. With the development of more therapy options, patients who failed in prior therapy hope to clear hepatitis C virus by undergoing a more effective retreatment regime. In this report, we investigated response rates to combination therapy [standard IFN-alpha or PEG-IFN-alpha and ribavirin] in patients who relapsed or failed in prior therapy.', 'Ninety-three patients were included in this retrospective study. All patients failed to previous IFN-alpha monotherapy (n=55) or to a combination of standard IFN-alpha and ribavirin (n=38). Fifty-nine patients were nonresponders and 34 were relapsers. Thirty-five patients were retreated with standard IFN-alpha plus ribavirin and 58 received PEG-IFN-alpha combination therapy.', 'Sustained virologic response (SVR) was induced in 31% of all patients. The highest SVR rate (58%) was observed in relapsers to standard IFN-alpha combination therapy who were retreated with PEG-IFN-alpha combination therapy. The SVR rate in relapsers to standard IFN-alpha monotherapy who received a standard IFN-alpha combination therapy was 50%. Relapsers responded in a significantly higher proportion to retreatment than nonresponders (56% vs. 17%, P<0.001). Relapse to previous therapy was identified as an independent predictor for therapy response. The lowest SVR rate was observed in nonresponders to standard IFN-alpha combination therapy who were retreated with PEG-IFN-alpha combination therapy (1/26; 4%).'] Is relapse to prior therapy the most important factor for the retreatment response in patients with chronic hepatitis C virus infection?