The treatment of chronic hepatitis C forms a considerable burden for society. The present standard treatment with PEG-Interferon and Ribavirin is costly, has side effects and is not always effective. The current trend is to prolong treatment from 24 to 48 or even 72 weeks in patients infected with genotypes 1 and 4 virus, in order to prevent relapses after cessation of therapy. There are, however, suggestions that treatment of relapses gives a response rate similar to that of first-time treatment. We, therefore, compared the sustained response rates and the mean treatment durations of one-time treatment and cyclic treatment in a model that incorporates the rates of non-response to antiviral therapy, of breakthrough during and of relapse after cessation of treatment. Our calculations show that, even under the most unfavourable assumptions, repeated 6-month treatment lowers the mean treatment duration from 9.6 to 7.5 months when compared to a single 12-month treatment, without jeopardising the overall effectiveness. If the results of our model calculations can be confirmed, current guidelines for the treatment of infections with genotype 1 hepatitis C virus ought to be reconsidered.