OBJECTIVES: The AIDS Pegasys Ribavirin International Coinfection Trial (APRICOT) demonstrated the efficacy and safety of peginterferon alfa-2a plus ribavirin (RBV) and interferon alfa plus ribavirin (IFN/RBV) in patients co-infected with HIV-HCV. However, the cost-effectiveness of treating CHC with peginterferon alfa-2a/RBV in this patient population has not assessed from the Spanish National Healthcare System (NHS) perspective. The objective was to establish the clinical prognosis, costs and cost-effectiveness of peginterferon alfa-2a (180 mcg/week) plus RBV versus IFN (3 million IU, three times a week) plus RBV, in patients with HIV-HCV co-infection from a Spanish national healthcare system (NHS) perspective. METHODS: A Markov model was developed to simulate the disease progression of 40-year old patients with HIV-HCV co-infection. Fibrosis progresión rates were obtained from published studies. Efficacy, in terms of sustained virological response (SVR), for peginterferon alfa-2a plus RBV and IFN/RBV in patients with genotype 1, genotypes 2/3 and genotypes 1/2/3 was obtained from APRICOT. Transition probabilities and quality of life estimates were obtained from published literature. Unit costs were obtained from a Spanish database. Cost and outcomes were discounted by 3.5% annually. RESULTS: In genotype 1 patients, peginterferon alfa-2a plus RBV compared with IFN/RBV increases patientxs life expectancy by 1.27 years (0.77 quality-adjusted life years (QALYs)), yielding an incremental cost-effectiveness ratio (ICER) of €3,677/life year gained (LYG) (€6,077/QALY gained). In genotypes 2/3 patients, peginterferon alfa-2a plus ribavirin increases life expectancy by 4.63 years (2.33 QALYs), yielding an ICER of 569 €/ LYG (€1,130/QALY gained). In genotypes 1/2/3 patients, the ICER is €1,487/ LYG (€2,762/QALY gained). CONCLUSION: From the Spanish NHS perspective, peginterferon alfa-2a (40KD) (PEGASYS®) plus ribavirin (COPEGUS®) in patients with HIV-HCV co-infection is a cost-effective treatment option, regardless of HCV genotype.