Open reading frame (ORF) 26 of human herpesvirus-8 (HHV-8) from peripheral blood samples of 15 Hungarian HIV-positive patients with or without Kaposi's sarcoma (KS) were amplified and sequenced. Four variants of HHV-8 were identified according to ORF 26 genotyping. Most of the samples were shown to be subtype A3, however, subtypes A, B3/C2/C2', and C3 (ORF 26 region) were also identified. The ORF 26 subtypes A and C3 of HHV-8 were only recovered from patients with KS while A3 was dominant in KS negative cases. The amplification of the hypervariable ORF K1 gene was successful only from 2 of the same 15 patients. Sequence analysis of the amplified ORF K1/VR1 regions identified subtype A3 from 2 patients with AIDS-associated KS. A novel ORF K1/VR1 variant belonging to subgroup A' was detected in a different sample in one of them. Amplification of the ORF K15, another representative locus for HHV-8 genotyping, was not successful from any of the peripheral blood samples. Unsuccessful amplification of the terminal K1 and K15 ORFs from peripheral blood samples suggests that KS biopsy specimens are needed for complete genotyping of HHV-8 strains from Hungary.