Hemophiliacs receiving multiple coagulation factor concentrate transfusions are prone for blood transmitting viruses' infections, including hepatitis C virus (HCV). The aim of the study was to estimate the incidence of HCV infection and to analyse HCV genotypes in hemophiliacs in Poland before HCV prevention in blood concentrates has been introduced. The study involves 58 children with hemophilia treated with more than 10 coagulation factor concentrate transfusions. The antibodies against HCV proteins were measured by the second generation assay (Organon Teknika). HCV-RNA particles and their genotypes were detected by nested PCR method and line probe assay (Inno-Lipa HCVII). Thirty cases (51.7%) were positive for antibody against HCV and only six (10.3%) were positive for HCV-RNA as detected by PCR. All six cases were infected with HCV with a single genotype, including type 1a in one, type 1b in four, and type 3a in one patient. Very rare in Poland HCV genotype 3a has been found in one patient receiving transfusions of imported coagulation factor concentrates. It is concluded, that high frequency of HCV infection in hemophiliacs is due to multiple blood derivatives transfusions, as evidenced by incidence of genotype 1b of HCV, which is prevalent in Poland. Moreover the risk for HCV infection increased with the duration of the disease. Most of the HCV infected hemophiliacs eliminated spontaneously HCV virus from the peripheral blood.