Hepatitis C virus is the leading cause of acute and chronic liver disease in hemodialysis patients. There are at least six major HCV-genotypes, with a well documented geographical distribution in the general population. Moreover, HCV-genotype is one of the major determinants of the therapeutic response to Interferon Alpha in affected patients. Since the therapeutic outcome in HCV-positive hemodialysis patients, especially with regard to the different HCV-genotypes, is of interest, a multicentre epidemiologic study was performed in HCV-antibody positive hemodialysis patients of two geographically remote countries, i.e. in Flanders (Belgium) and in Saudi-Arabia. 184 chronic hemodialysis patients, with a positive second or third generation Elisa assay for HCV, were tested for HCV-viremia and HCV-genotype, using a 5' untranslated region (UR) nested PCR for the detection of HCV-RNA and subsequently type-specific probes to hybridize with HCV-RNA (Inno-Lipa). Additionally, clinical data were collected by means of a standardized questionnaire, thoroughly completed by the nephrologist in charge of each respective patient. Viremia was present in 79% of the patients (146 out of 184). The prevalence of HCV-genotypes differed significantly between Belgian and Saudi-Arabian dialysis-patients. In Belgian dialysis patients HCV-genotype 1b was most prevalent (i.e. 62%), while in Saudi-Arabian patients HCV-genotypes 4, 1b, and la were present in respectively 36,4%, 31,7%, and 25,8% of the HCV-PCR positive patients. Although there were significant differences between Belgian and Saudi-Arabian dialysis patients, no clinical data showed any significant correlation with the HCV-genotype. Transaminases, determined over a six months period, showed normal average values. Doubling of the transaminases, in at least one out of six measurements over a six monthly period, occurred only in 14% (alanine aminotransferase, ALT) and 10% (aspartate aminotransferase, AST) of the patients. In Belgian dialysis patients, HCV-genotype 4 (or HCV-genotype 5) significantly correlated with a more recent start of dialysis treatment. We conclude that there is a significant different geographical prevalence of HCV-genotypes in HCV-affected hemodialysis patients. None of the different HCV-genotypes shows any particular clinical expression. Transaminases are not a sensitive marker for ongoing HCV-replication in hemodialysis patients. In Belgian dialysis patients, a changing pattern of HCV-infection is suggested, with an increasing prevalence of HCV-genotype 4 (or HCV-genotype 5) in more recent years. These data suggest possible implications for the therapeutic strategy in dialysis patients.