OBJECTIVE: To evaluate the prevalence of infection by HCV among hemophiliacs in the State of Pará (Brazil), and its possible relation to hepatic enzymes serum level, type of hemophilia involved, age, level of severity, kinds and combinations of treatment, as well as date in which treatment with hemoderivates was started.METHODS: Cross-sectional epidemiological investigation, analyzing 62 hemophilic patients of the Centro de Hemoterapia do Pará (HEMOPA), all born after 01/01/80, by means of the review of the medical records, physical examination and laboratory tests: Anti-HCV (ELISA 3.0), polymerase chain reaction - PCR - (HCV-RNA), and dosage of transaminases serum levels. Statistical analysis was carried out using Chi-square and Fisher's Exact Test, the results being considered significant if p</=0.05.RESULTS: Out of the 62 patients analyzed, 48.4% (n=30) were HCV positive. Among these patients, 43.3% (n=13) presented viraemia with detection of viral RNA using the PCR technique. HCV infection was related to the condition beginning of treatment before 1993 (p=0.0005); the type of hemophilia, being type A more frequent (p=0.028); the level of severity, with higher frequency in the moderate condition (p=0.026); and age, with higher frequency among those who were older than 5 years of age (p=0.025).CONCLUSION: Infection by HCV among hemophiliacs in the State of Pará is high (48.4%) and was related to the beginning of the treatment before 1993, when obligatory serological trial for HCV was introduced in Brazilian blood banks. It is also significantly more frequent in children over five, with type A hemophilia of moderate gravity.