SummaryThe effects of pentachlorophenol (PCP) and 2-chlorophenol (2CP) on white rot fungi,Abortiporus biennis, Cerrena unicolor, Gloeophyllum odoratum, andTrametes versicolorwere investigated. With the exception ofC. unicolorandA. biennis, concentrations of PCP higher than 50 ppm inhibited fungal growth completely. However, extreme concentrations of PCP (500 ppm) caused a 61% increase in growth ofC. unicolorcompared to the control culture within 14 days. When initial PCP concentrations were 50 ppmA. biennisandC. unicolorachieved, respectively, 87% and 78% of chlorophenol transformation within 3 days. However, when 2,5-dimethylaniline (0.2mM) was added to theC. unicolorculture, 98% of PCP transformation was achieved after one hour. Under the same conditions,A. biennistransformed 44% of PCP. Both chlorophenols are completely removed, when laccase activity reaches its maximum. In conclusion, among the four fungi investigated,C. unicolorandA. Bienniswere very effective in transforming PCP and 2-CP. This biotransformation was greatly intensified by 2,5-dimethylaniline and accompanied by an increase in laccase activity.