The 18S rDNA nucleotide sequences of 25 Sporobolomyces species and five Sporidiobolus species were determined. Those of Sporobolomyces dimmenae JCM 8762T, Sporobolomyces ruber JCM 6884T, Sporobolomyces sasicola JCM 5979T and Sporobolomyces taupoensis JCM 8770T showed the presence of intron-like regions with lengths of 1586, 324, 322 and 293 nucleotides, respectively, which were presumed to be group I introns. A total of 63 18S rDNA nucleotide sequences was analysed, including 33 published reference sequences. Sporobolomyces species and the other basidiomycetes species were distributed throughout the phylogenetic tree. The resulting phylogeny indicated that Sporobolomyces is polyphyletic. Sporobolomyces species were mainly divided into four groups within the Urediniomycetes. The groups are designated as the Sporidiales, Agaricostilbum/Bensingtonia, Erythrobasidium and subbrunneus clusters. The last group, comprising four species, Sporobolomyces coprosmicola, Sporobolomyces dimmenae, Sporobolomyces linderae and Sporobolomyces subbrunneus, forms a new and distinct cluster in the phylogenetic tree in this study.