Combination therapy of chronic hepatitis C with interferon alpha and ribavirin has been proven to be highly effective in naive and relapse patients with two to ten-fold increase of the response rate. However, combination therapy of primary non-responders to interferon alpha is discussed controversially. Therefore, to analyze the response rate to retreatment with a combination therapy with interferon alpha and ribavirin, we compared data of 555 patients described in 23 publications to the data of 16 non-responders treated in our center. The patients received interferon alpha (at least 3 MU tiw) and ribavirin in a dose of 1,000/1,200 mg per day. At the end of treatment 14% of our patients had normal ALT values and were HCV-RNA-negative compared to 34% of all patients described in the literature. In our patients the viral load decreased from 1,110 +/- 670 x 10(3) copies/ml prior to therapy to 300 +/- 480 x 10(3) copies/ml at the end of treatment (p = 0.002). After a follow-up period of six months quantitative RNA-levels rose again to 1,485 +/- 755 x 10(3) copies/ml. Whereas only 7.4% (24/325) of all patients described showed a response with normal ALT values and negative HCV-RNA at the end of follow-up, no sustained response was observed in our patients. In contrast to naive and relapse patients, the response rate of combination therapy in patients previously not responding to interferon alpha alone is only low. Thus, standard regime (IFN 3MU twi plus ribavirin for six months) as a regular therapy for non-responders is not recommended.