INTRODUCTION: Hepatitis C virus (HCV) infection is potentially curable, but the sustained virological response (SVR) has been shown to be lower in patients coinfected HIV. A single-centre experience treating individuals with HCV and HIV coinfection is reported.METHODS: Twenty-one patients who received standard doses of pegylated interferon with weight-based dosing of ribavirin (mean 14.3 mg/kg) were retrospectively reviewed. Qualitative HCV polymerase chain reaction (PCR) was performed prospectively every four weeks if the patient remained HCV PCR positive. All patients with HCV genotype 1 were treated for 48 weeks. Patients with genotype 2 or 3 were treated for 24 weeks and 32 weeks to 36 weeks if their HCV RNA level was undetectable after four weeks (RVR4) or eight weeks (RVR8) of therapy, respectively. If RVR8 was not achieved, the treatment was continued for 48 weeks.RESULTS: There were no dropouts or dose reductions within the first 12 weeks of treatment. SVR status was available for 20 patients and adequate serum for viral kinetics analyses was available for 17 patients. Eighty per cent of the patients achieved SVR (50% genotype 1; 100% genotypes 2 and 3). The week 8 viral load remained elevated for all genotype 1 nonresponders.DISCUSSION: High effectiveness rates were seen, particularly in patients with HCV genotype 2 and 3 who were treated for shorter durations. HCV viral loads after eight weeks of therapy helped distinguish patients with HCV genotype 1 who would respond to therapy.