Background and Objective: Although transfusion therapy has lead to great improvement in longevity for hemophiliacs, but there have been tragic setbacks especially from transmission of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) .HIV was reported to increase the rate of HCV-related liver failure by 4.2 times. In this study, we aimed to determine the seroprevalence of HIV and HCV, the association of HCV with abnormal liver tests, impact of HIV on HCV-related abnormalities and the distribution of HCV genotypes in Iranian hemophiliacs. Patients and Methods: In a cross-sectional study, we determined virological, clinical and epidemiological characteristics for HIV and HCV infection of 236 hemophiliacs attending our center. Data were analyzed using Chi-square test. Results: Ten (4.7%) out of 211 patients tested were HIV seropositive and 145 (83.3%) were HCV seropositive. All tested positive HIV patients also had HCV. HCV seroprevalence was significantly higher in patients with hemophilia A and B as compared to other congenital coagulopathies and it was directly related to coagulation severity. HCV seroprevalence was lower in hemophiliacs with positive HBsAg (p = 0.03) but it did not differ by HBcAb or HBsAb results. HCV genotype 1a (48.5%) was predominant type and genotype 3a (33.3%) was also common. Frequency of abnormal aspartate aminotransferase and alanine aminotransferase liver enzymes was significantly higher in the HCV positive group (p = 0.006). Conclusion: This study provides evidence that hepatitis c virus infection is a major problem for Iranian hemophiliacs and it has higher prevalence in hemophiliacs with higher age, more severe coagulopathies, abnormal alanine aminotransferase level, and human immunodeficiency virus co-infection.