4-Nonylphenols (NPs) are endocrine disrupting compounds (EDCs) which are known to interfere with the endocrine system of humans and animals. The aim of this study was to test the ability of non-ligninolytic filamentous fungus Gliocephalotrichum simplex to biodegrade 4-n-NP. The results revealed that during the first 24 h of incubation, 4-n-NP at the concentration of 50 mg L-1 was eliminated from the culture medium by 88%, whereas at the concentration of 100 mg L-1 by 50%. In this paper, glucose utilization as a co-substrate during toxic compound degradation was also shown. It was found that the presence of 4-n-NP caused sugar metabolism retardation and this inhibition was dependent on NP concentration. The qualitative GC-MS analysis showed the presence of products of G. simplex 4-n-NP biodegradation. We proposed the metabolic pathway of 4-n-NP biodegradation, which is based on subsequent Cl removals from the alkyl chain followed by the aromatic ring cleavage. In further experiments with 4-n-NP [ring-C-14(U)] we proved aromatic ring cleavage occurrence. After 72 h of incubation the evolution of (CO2)-C-14 was observed and the mineralization efficiency was on the level of 29%. The results suggest the existence of a novel mechanism of 4-n-NP degradation in fungi. (C) 2010 Elsevier B.V. All rights reserved.