Metabolism of 2, 3-, 2, 4-, 2, 5-, 2, 6-, 3, 4- and 3, 5-dichloro-1-nitrobenzenes by Mucor javanicus and metabolites of 2, 4-dichloro-1-nitrobenzene (2, 4-DCNB) by seven fungi were investigated. The dichloronitrobenzenes were reduced predominantly to the corresponding benzenamines by M. Javanicus. In addition to the benzenamine derivatives, minor metabolites in which an ortho-chlorine atom was substituted with a methylthio group were detected in the medium of M. javanicus administered 2, 3- and 2, 4-DCNB. More or less amounts of 2, 4-dichlorobenzenamine and 4-chloro-2-methylthio-1-nitrobenzene were detected as metabolites of 2, 4-DCNB also in the media of M. griseo-cyanus, M. hiemalis, M. praini and Aspergillus flavus.