It has been found that numerous yeast-like microorganisms from the genera Geotrichum, Trichmporon, Candida, Rhodotorula and Sporobolomyces occurring in wastewater treatment systems biocenoses arę able to utilize aniline, p-nitroaniline and acetanilide as a sole C-source. High active in this respect were strains belonging to the species of Geoirichum candidum, G. sericeum and Candida boidinii.