The sequences of the D1/D2 region of 26S rDNA from seven Sporobolomyces species, Bensingtonia subrosea, and Rhodosporicium toruloides were determined and compared with those from representatives of the genera Leucosporidium, Rhodosporidium, Rhodotorula, and Sporidiobolus. The five species of Sporobolomyces analyzed were distantly related to a monophyletic clade consisting of species of Sporidiobolaceae and Sporobolomycetaceae. Sporobolomyces falcatus was found to be closely related to Tremella exigua. The members of Sporidiobolaceae and Sporobolomycetaceae were divided into four groups. Group 1 was composed of Leucosporidium scottii and two Rhodotorula species, and group 2 contained three Rhodotorula species. Group 3 was designeate as the Sporobolomyces/Sporidiobolus core group, as it contained Sporidiobolus johnsonii, the type species of Sporidiobolus and the teleomorphic state of Sporobolomyces salmonicolor (the type species of Sporobolomyces). Group 4, named the Rhodotorula/Rhodosporidium core group, included Rhodosporidium toruloides and Rhodotorula glutinis, the type species of the genera Fhodosporidium and Rhodotorula, respectively. The four groups were differentiated on the basis of their physiological characteristics including the assimilation of D-glucosamine, glucuronate, 2-keto-gluconate, L-arabinitol, raffinose, methyl-$alpha$-glucoside, and satrch. The taxonomy of the genera Leucosporidium, Rhodosporidium, Rhodotorula, Sporidiobolus, and Sporobolomyces will require a major revision when more data becomes available.