Growth of the bioremediation fungus Phanerochaete chrysosporium in non-sterilised soil stimulated the release of sulphate and ammonium from added sulphur-coated urea and also significantly increased ammonium release (but not subsequent nitrification) from added urea. The mineralisation of mycological peptone to ammonium in soil and its subsequent oxidation to nitrate was also generally stimulated following inoculation. The results show that following inoculation, P. chrysosporium influences the transformation of natural or fertiliser compounds in soils. The possibility that such changes may occur should be considered when P. chrysosporium is added to soils solely for the purposes of bioremediation.