The route of degradation of acrinathrin has been investigated by Diehl in four soils using two different radio- labelling positions (benzyl- and dimethyl-label). Results from Hawkins (1990) were not validated due to poor mass balance. The soils from Diehl (2002) covered a range of characteristics (pH 5.5 – 7.8, OC 0.5% - 2.3%, texture sand – silt loam). Acrinathrin was metabolised in soil with the primary degradation step being cleavage of the fluoropropyl side chain to form DP-A, followed by further cleavage leading to the formation of 3-PBAc. The majority of the radioactivity was ultimately found as bound residues (max. 26.7 % AR for benzyl and 50.4% AR for dimethyl, 120 days) and CO2 (max. 68.8% AR for benzyl and 48 % AR for dimethyl, 120 days). The DP-A metabolite was 􏰆1% AR in four soils. The metabolite 3-PBAc occurred at a maximum of 1.4% AR. Three other unidentified components were also detected in soil, none of which individually exceeded 2.2% of applied radioactivity. All components were detected at very low levels (<5% AR) and were extremely transient in soil. Degradation of acrinathrin seemed to be lower in the sandy loam soil. Additionnal information was provided by the dark control from the photodegradation study. The dark control, which was incubated in the same conditions as for aerobic degradation studies, showed that extractable radioactivity was more important (94.8% after 30 days). Four main metabolites are identified. Metabolites DP-A and DP-A-A are considered as major as they reached respectively 9.7 and 10.5% AR at 30 days. Metabolite DP- DPB-A is a non-transient minor metabolite (5.7 and 7.6% AR at 21 and 30 days respectively). Metabolite A-A must be considered as it did not reach its maximum at the end of the study (5.7% at 30 days). Mineralisation and unextractable radioactivity are much lower than in Diehl study as their maximum are 0.2% and 8% respectively at 30 days.