Within a screening program, 91 fungal strains belonging to 32 genera of different ecological and taxonomic groups (wood- and litter-decaying basidiomycetes, saprophytic micromycetes) were tested for their ability to metabolize and mineralize 2,4,6-trinitrotoluene (TNT). All these strains metabolized TNT rapidly by forming monoaminodinitrotoluenes (AmDNT). Micromycetes produced higher amounts of AmDNT than did wood- and litter-decaying basidiomycetes. A significant mineralization of [C-14]TNT was only observed for certain wood- and litter-decaying basidiomycetes. The most active strains, Clitocybula dusenii TMb12 and Stropharia rugosa-annulata DSM11372 mineralized 42% and 36% respectively of the initial added [C-14]TNT (100 mu M corresponding to 4.75 mu Ci/l) to (CO2)-C-14 within 64 days. Micromycetes (deuteromycetes, ascomycetes, zygomycetes) proved to be unable to mineralize [C-14]TNT significantly.