Abstract: The effects of cytochrome P450 inhibitors on biotransformation of organochlorine pesticide chlordane by white-rot fungus Phlebia lindtneri during 15 days of incubation was investigated using piperonyl butoxide(PBO) and 1-aminobenzotriazole(ABT).In contrast to the degradation of chlordane in cultures without inhibitors,degradation of chlordane was inhibited at a rate of about 60% in cultures with 1.0 mmol/L PBO or ABT,and the accumulation of most metabolites clearly decreased,except heptachlor and dichlorochlordene,which showed a markedly increase in cultures with inhibitors.Moreover,PBO and ABT efficiently inhibited degradation of the metabolites of chlordane,heptachlor,dichlorochlordene and oxychlordane,but had no effect on degradation of heptachlor epoxide.These results indicated that fungal cytochrome P450 enzymes involved in some steps of chlordane transformation,especially in the hydroxylation,epoxidation and hydrolysis process.