Hepatitis C virus (HCV) infection is a common cause of liver disease among polytransfused thalassemics. We treated a cohort of subjects with beta-thalassemia major and chronic hepatitis C with alpha-interferon. The aims of the study were to assess the long-term biochemical and virologic efficacy of alpha-interferon and to evaluate the influence of HCV type and liver siderosis on the outcome of therapy. Seventy subjects (mean age, 14.1 years) with chronic HCV infection and abnormal aminotransferases received recombinant alpha-interferon for 12 months and were observed after therapy for at least 24 months. Sixty-three subjects (90%) were HCV-RNA positive at the start of therapy. HCV type 1b was found in 41 subjects (65.1%), non-1b types in 13 (20.6%), and mixed HCV types in 9 (14.3%). Liver biopsy showed cirrhosis in 11 subjects (15.7%) and siderosis grade 3-4 in 24 patients (34.2%). Three patients stopped therapy due to adverse events. Twenty-eight subjects (40%) had normal aminotransferases and had cleared HCV-RNA when last observed (mean follow-up, 36.5 months; range, 25 to 49 months). Of 41 patients who did not normalize aminotransferases, 9 had become HCV-RNA negative at the end of follow-up. The absence of cirrhosis, low liver iron content, and infection with non-1b HCV type were independently associated to complete sustained response upon multivariable analysis. In conclusion, alpha-interferon may induce a sustained virologic and biochemical remission of hepatitis in beta-thalassemic patients with chronic HCV infection and nonadvanced liver disease.