Basidiomycetous yeasts of smut affinity and yeast phases of smut fungi are sensitive to the Rhodotorula mucilaginosa mycocins. Ascomycetes, except predominantly Hanseniaspora a spp., tremelloid yeasts, and tremelloid fungi are resistant. Mycocins of killers of the carbonei group have the most narrow spectrum of action: representatives of the genera Microbotryum, Rhodosporidium, Sphacelotheca, and Sporidiobolus and Sporobolomyces roseus are sensitive to them. The action spectrum of killer toxins of the rubra group includes the Bensingtonia and Leucosporidium species, and that of groups mucilaginosa and ukrainica includes Entyloma and Kondoa. The spectrum of mycocins of the grinbergsii group is the widest: they are also active against the Agaricostilbum, Sterigmatomyces, and Tilletiopsis species. Grouping of yeasts according to their sensitivity to mycocins correlates with the composition of the extracellular polysaccharides and data of RNA sequencing. Formation of teleospores was found upon crossing of very close or identical cultures according to their sensitivity to mycocins (Apiotrichum osvaldii, B. intermedia, Sp. tenuis). No plasmid RNAs or DNAs were found in the cells of mycocinogenic strains of Rh. mucilaginosa.