The white-rot fungus Phanerochaete chrysosporium has demonstrated abilities to degrade many xenobiotic chemicals. In this study, the degradation of three model polychlorinated biphenyl (PCB) congeners [4,4'-dichlorobiphenyl (DCB), 3,3',4,4'-tetrachlorobiphenyl (TCB), 2,2',4,4',5,5'-hexachlorobiphenyl (HCB)] by P. chrysosporium in liquid culture was examined. After 28 days of incubation, 14C partitioning analysis indicated extensive degradation of the DCB including 11% mineralization. In contrast, with the TCB and HCB there was negligible mineralization and little evidence for any significant metabolism. With all of the model PCBs, a large fraction of the 14C was determined to be biomass-bound. Results form a time course study done with 4,4'-[14C]DCB to examine 14C partitioning dynamics indicated that the biomass-bound 14C was likely attributable to non-specific adsorption of the PCBs to the fungal hyphae. In a subsequent isotope trapping experiment, 4-chlorobenzoic acid and 4-chlorobenzyl alcohol were identified as metabolites produced from 4,4'-[14C]DCB. To the best of our knowledge, this the first report describing intermediates formed by P. chrysosporium during PCB degradation.