Electrophoretic karyotyping of the two most widely studied strains of Phanerochaete chrysosporium, BKMF-1767 and ME-446, has been determined using transverse alternating field electrophoresis. The genomic DNA of BKMF-1767 was resolved into 10 chromosomes ranging in size from 1.8-5.0 Mb, amounting to a total genome size of about 29 Mb. The genomic DNA of strain ME-446, on the other hand, was resolved into 11 chromosomes, amounting to a total genome size of about 32 Mb. Lignin peroxidase genes have been localized to five chromosomes in strain BKMF-1767 and to four chromosomes in strain ME-446.