GB virus C (GBV-C) has been detected in Belgian hemodialysis patients. To study their genomic diversity and phylogenetic relationship, a 592 nucleotide fragment extending from the 5' non-coding region to part of the E1 gene of the GBV-C genome was amplified and sequenced from 12 Belgian hemodialysis patients in two different centers. Together with strains from different geographical origins, these sequences were analyzed phylogenetically using three different methods. A consistent tree topology was obtained with all methods. Three GBV-C genotypes were observed with two subtypes in type 2 and a questionable subtyping in type 1. Except for one isolate falling into type 1 cluster which mainly consists of African strains, all the other Belgian strains clustered within the type 2a branch. Two GBV-C isolates in two patients from the same hemodialysis center clustered together closely, suggesting a nosocomial transmission. In view of their long branch length, it seems unlikely that the other Belgian strains evolved recently from a common ancestor. Our results indicate that the major type circulating among Belgian hemodialysis patients seems to be 2a, which is usual for Europe and North America, but that the African type 1 also exists to a minor extent. Although patient to patient transmission of GBV-C in Belgian hemodialysis centers did occur, it may not account for the majority of infections.