The environmental fate of penflufen was investigated in a number of laboratory studies using material radiolabeled in the phenyl (UL) or the 3 position of the pyrazole ring. Results of laboratory aerobic route and rate of degradation studies carried out at 20°C are available for four European soils (120 days duration) and at 25°C for two US soils (365 day duration). Two major metabolites (>10% AR) were detected under aerobic conditions, the first was identified in both the European and the US soils, but the second was only evident from the US soils and wasn’t formed until after the European soil study had finished. They were identified as penflufen-3-hydroxy-butyl which peaked at 16.0% AR after 273 days at 25°C and Penflufenpyrazolyl- AAP at 11.5% AR also after 273 days at 25°C. Mineralisation in the six soils ranged between 1.5% AR and 6.5% AR at 20°C (after 120 days) and between 7.9% and 9.8% AR at 25°C (after 365 days). Non extractable residues were between 11.4% AR and 19.3% AR at 20°C (after 120 days) and between 17.6% and 25.8% AR at 25°C (after 365 days).