Cladosporium sp. strain AJR(3)18,501 was isolated from DDT-contaminated soil by its ability to decolourise the polymeric dye, Poly R-478. When inoculated into potato/dextrose broth containing 100 mg of DDT l(-1), a 21% decrease in DDT concentration was observed 12 days after its addition, however, no transformation products were detected by gas chromatography. TLC of culture medium and mycelia extracts revealed 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane and five unknown transformation products associated with the mycelia.