The electrophoretic karyotype of three different strains of Phaffia rhodozyma was determined by contour-clamped homogeneous electric field (CHEF)-gel electrophoresis. Significant differences in electrophoretic karyotyping patterns were found among the three strains studied. Between nine and 17 bands were observed. The size of these bands, based on their migration relative to the chromosomal DNA of Schizosaccharomyces pombe, Hansenula wingei was estimated to be between 0.48 and 3.1 Mb.