Standard therapy for chronic hepatitis C (HCV) is pegylated interferon in combination with ribavirin. There is limited experience with either drug in dialysis [end stage renal disease (ESRD)]. Six haemodialysis patients, four with HCV genotype 1, one with genotype 4 and one genotype 2 were treated with pegylated interferon-alfa-2b (n = 4) and pegylated interferon-alfa-2a (n = 2) for 24-48 weeks according to genotype with a dose of 50 or 135 mug/week respectively. All patients were given reduced ribavirin doses, initially 200-400 mg/day. Ribavirin trough plasma concentrations were measured with a HPLC method previously developed for earlier treatment studies, aiming at a target concentration of 10-15 micromol/L. Interferon related side-effects were common, in one patient peg-alfa-2b was permanently reduced to 50 mug every 9-10 days with improvement in tolerance. Average ribavirin dose was 170-300 mg/day. Ribavirin-induced anaemia was treated with high doses of erythropoietin and low doses of iron. Blood-transfusions were not needed. All patients became HCV-RNA-PCR negative during treatment which was completed or nearly completed in four patients. One patient terminated therapy prematurely due to pronounced interferon related side-effects and another died of myocardial infarction probably not related to therapy. Three patients have remained HCV-RNA negative with extended follow-up, two of whom have had a successful kidney transplant. Pegylated interferons are likely to become a valuable addition for HCV therapy in ESRD and are possible to combine with ribavirin. However the pharmacokinetics and tolerability of both peg-alfa-2a and 2b need to be studied more closely in prospective studies before definite dosing recommendations can be made.