Objective: The main objectives of this study were to investigate the prevalence of hepatitis C virus (HCV) among patients with β-thalassemia major and to determine the most prevalent genotype for this virus. Materials and Methods: One hundred twenty-two β-thalassemia major patients who were previously diagnosed at the molecular level were included. All plasma samples were tested for the presence of antibodies by ELISA. Real-time polymerase chain reaction (PCR) was used in the quantitation the HCV RNA viral loads, and consequently, patients with high virus titer were genotyped by the linear array. Results: Forty of the patients were anti-HCV positive. The prevalence of anti-HCV was significantly higher in patients who received blood transfusion before 1993 (83.7%) than in those who received it after 1993 (16.3%) (p=0.000). β-thalassemia major patients with HCV infection had significantly higher rates of elevated aspartate aminotransferase (54.4% vs 40.5%, p=0.045) and alanine aminotransferase (72.47% vs 37.47%, p=0.00) and of splenectomy (54.8% vs 45.2%, p=0.004) than β-thalassemia major patients without HCV. Conclusion: HCV genotype 4 is the commonest genotype in multi-transfused patients with β-thalassemia major in Jordan. (Turk J Hematol 2011; 28: 47-51) Key words: Virology, transfusion, thalassemia Received: August 7, 2009 Accepted: February 22, 2010 Özet Amaç: Bu çalışma kapsamında, β-talasemi majörlü hastalarda HCV prevalansının araştırılması ve bu virüsün söz konusu hastalar arasında en yaygın genotipinin belirlenmesi amaçlanmaktadır. Yöntem ve Gereçler: Önceden moleküler düzeyde tanı konan 122 β-talasemi majörlü hasta çalışmaya alınmıştır. Tüm plazma numuneleri antikor varlığına yönelik olarak ELISA ile test edilmiştir. HCV RNA