In all systems the total radioactivity recoveries ranged from 88 - 101%AR. In the majority of samples the mass balance was greater than 97%AR. At the end of the 12 month incubation period, 50.5, 5.0 and 14.3%AR was recovered as 14CO2 from the sandy loam, silty loam and silty clay loam soils, respectively. Extractable residues decreased over time and accounted for 22.5, 70.4 and 25.9% AR respectively in the same soils and after the incubation period. Conversely, unextractable residues increased with time reaching values of 26.0, 24.5 and 53.4%AR, respectively, after 12 months. In addition to undegraded fenvalerate that represented at the end of the study, respectively, 16.6, 32.4 and 11.7% AR 4′-OH-Fen, CPIA, CONH2-Fen and several other minor metabolites were detected in the three soils tested. CONH2-Fen was observed as the major metabolite formed and reached up to 32%AR in the silty clay loam soil and 10% in the silty loam soil at the end of the study. It is suggested that to some extent hydrolysis of unextractable residues gives rise to CPIA.