Abstract Permethrin was degraded in a variety of soils, the rate depending on soil type and previous treatment. Degradation in shaken aqueous soil suspensions was faster than in moist soil, probably due to the better redistribution of the permethrin. Degradation was apparently biological, as it was prevented by heat sterilisation, anaerobic conditions and sodium azide. In soil, repeated dosing, addition of inorganic N, P or K, sucrose or cellulose had little effect on degradation. Bacteria were isolated that were able to oxidise the permethrin hydrolysis product, 3-phenoxybenzyl alcohol, but not permethrin itself.