Raw city sewage irrigation seems to affect population densities of keratinophilic fungal communities, with the highest population densities being found in the heavily polluted field soils, while the lowest population densities occur in non-polluted field soils. However, basic similarities in the biodiversity of keratinophilic fungal communities exist in both non-polluted and polluted field soils and raw city sewage. Comparable numbers of fungal species exist in these habitats, and the species most commonly found include Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus. Field soils receiving either raw city sewage or normal irrigation water were shown to be rich in pathogenic and potentially pathogenic keratinophilic fungi, including dermatophytes, with raw city sewage yielding the highest percentage, followed by moderately polluted fields, non-polluted fields, and heavily polluted fields. Dermatophytes and their related fungi recovered from these habitats include Microsporum gypseum, Trichophyton ajelloi, Arthroderma cuniculi, A. curreyi, Chrysosporium keratinophilum, C. tropicum and C. pannorum. The ability of 55 cycloheximide-resistant fungal species (117 isolates) to degrade human hair in vitro was investigated. The species were recovered from polluted (raw city wastewater-irrigation) and non-polluted (normal irrigation) field soils and raw city wastewater. The intensity of keratinolytic activity (IKA) was estimated on a scale of 0-100, based on morphological expression of keratinolysis. A high percentage of the species tested (48/55, 87%) demonstrated a varying degree of keratinolytic activity. Five species ( Chrysosporium keratinophilum, Microsporum gypseum, Penicillium frequentans, Rhizopus stolonifer, and Trichophyton ajelloi) showed strong IKA, and were capable of producing invasive structures related to radial penetration and surface erosion contemporaneously. On the other hand, seven of all the tested species, including Acremonium species, Aspergillus carneus, Nectria inventa, Penicillium citrinum, Paecilomyces variotii, Plectosphaerella cucumerina, and Verticillium nubilum, showed no keratinolytic activity. The keratinolytic activity of the following species is recorded in this study for the first time: Acremonium strictum, Chrysosporium pannorum, Cladosporium herbarum, Fusarium tricinctum, Gliocladium viride, Humicola fuscoatra var. fuscoatra, Nectria ventricosa, Penicillium griseofulvum, P. islandicum, Verticillium catenulatum, and V. psalliotae. Isolates of the same species can vary in their IKAs. Thus, such a characteristic does not seem to be constant or speciesspecific.