Background and study aims : In Belgium, 10-15% of patients infected with the human immunodeficiency virus (HIV) are coinfected with hepatitis C virus (HCV). Because of increased incidence of antiretroviral drug-related hepatotoxicity and more rapid clinical evolution towards end-stage liver disease, treatment of chronic hepatitis C becomes a priority. We report the results or a multi-centred Belgian study evaluating efficacy and safety of peginterferon alpha-2b plus ribavirin in HIV-HCV co-infected patients without AIDS and without decompensated liver disease. Patients and methods : Forty-one patients, all genotypes, were screened to participate. Eventually 37 received treatment with peginterferon alpha-2b (1.5 mu g/kg/week) plus daily weight-based ribavirin for 52 weeks. About one third of the patients were genotypes 1, 2/3, and genotype 4, most of the latter being of Central African origin. About 56% of the patients had severe fibrosis (Metavir score >= F3). Results : Sustained viral response (SVR) at 24 weeks of follow-up was observed in 10/37 (27%) of patients. SVR was higher in genotype 2/3 compared to genotype 1/4 (46.7% versus 13.6%; p = 0.06) and in low (F0-F1) versus high (F2-F4) grade fibrosis (p = 0.06). Treatment was withdrawn for side effects in 11/37 patients (30%). One Child A cirrhosis patient at the start of therapy died 7 months after treatment withdrawal as a result of severe haemolytic anaemia. Conclusions : It can be concluded that weight-based peginterferon alpha-2b plus ribavirin can be successful in selected HIV-HCV co-infected patients. Caution should be applied in patients with advanced liver disease. (Acta gastroenterol. belg., 2009, 72, 389-393).