Fluazinam is metabolised by microbial activity. The main metabolic pathway is the formation of bound residues, which were found in amounts of up to 47.2 % of applied radioactivity after 180 days in laboratory studies under standard conditions. Metabolites which would indicate cleavage of the bridging amino group were not observed. Mineralization (formation of CO2) amounted for up to 6 % applied radioactivity after one year under standard conditions. Under aerobic conditions HYPA was the major metabolite which is formed by hydrolysis of the phenyl ring chlorine of fluazinam to a hydroxyl group. The maximum amount found in laboratory studies under standard conditions was 13.9 % AR, after 48 days of incubation. MAPA and DAPA, which are formed by reduction of one or both NO2 groups, respectively, on the phenyl ring of fluazinam, were found in minor amounts. Under anaerobic conditions MAPA and DAPA were the major metabolites, whereas HYPA was found only in minor amounts. Degradation of fluazinam is accelerated and formation of NER is enhanced under anaerobic conditions but mineralization (CO2 formation) seems lower.