The environmental fate of diflufenican was investigated in a number of laboratory studies using either 2,4-difluorophenyl, 3-trifluoromethylphenyl or pyridine ring labelled material. Results of the laboratory aerobic route and rate of degradation studies carried out at 10, 20 or 22°C are available for six different soils. Two major metabolites (>10 % AR) were detected in aerobic conditions. They were identified as AE B107137 (2-(3-trifluoromethylphenoxy)nicotinic acid) which peaked at 16.78 % AR after 180 days at 10°C and as AE 0542291 (2-(3- trifluoromethylphenoxy)-nicotinamide) which peaked at 26.26 % AR after 320 days at 20°C. An additional minor metabolite peaked at 1.5 % AR after 52 weeks and was identified as metabolite 4 (3-hydroxymethyl-2-(3-trifluoromethylphenoxy)pyridine). Mineralisation to CO2 occurred up to 43.6 % AR and unextracted residues accounted up to 31 % after 120 days in silty clay loam for 3-trifluoromethylphenyl ring labelled diflufenican. Marginally lower levels of CO2 and unextracted residues were formed in studies preformed with the other two label positions, with levels between approximately 15 and 20% at 120 d.