Abstract: Eleven isolates of basidiomycetous yeast were obtained from Hyoscyamus muticus plants as endophytes; they were observed to comprise four Pseudozyma species based on morphological and physiological analyses. Molecular taxonomic analysis based on nucleotide sequences of the D1/D2 domain of the large subunit ribosomal RNA gene (D1/D2), internal transcribed spacer region of the rRNA gene (ITS) and mitochondrial rRNA genes (both large and small subunits) revealed that the four isolates represented distinct species and formed a cluster with Macalpinomyces ericachnes and Moesziomyces eriocauli (Ustilaginaceae). D1/D2 and ITS sequence analyses also indicated that the four isolates were genetically distinct from all known Pseudozyma species, suggesting that the isolates belonged to four new species.