The inosine triphosphatase (ITPA) gene and interleukin 28B (IL28-B) gene variants have been associated to protection of anemia and sustained virological response, respectively, in patients with chronic hepatitis C (CHC) during antiviral therapy. Aim of this study was to evaluate the single and combined role of both polymorphisms in the management of peg-interferon-ribavirin treatment in CHC patients. We studied 79 Italian patients with histology proven CHC treated with pegylated interferon plus ribavirin for 6-12 months on the base of HCV genotype. Patients were carefully followed-up for anemia development which was classified as mild, moderate or severe in relation to levels of haemoglobin decreasing; ribavirin dosage reduction and/or epoietin administration were carried out, where needed. Sustained virological response (SVR) was considered for HCV-RNA clearance after 6 months of treatment stop. Decay of haemoglobin at month 1 of treatment significantly correlated with ITPA activity (p 0.0004) and at multivariate analysis ITPA activity was the only parameter associate with anemia (R - 0.4; p 0.0004). SVR was obtained in 47% of patients. IL28B CC variant was associated with SVR (p 0.01), but IL28B polymorphisms had no influence on the ITPA polymorphism. This study confirms the role of ITPA variants in the prediction of development of severe anemia during antiviral treatment for CHC and demonstrates the absence of influence of IL28B variant on ITPA polymorphisms. These two polymorphisms can be useful in the management of patients that need antiviral therapy for HCV chronic infection.