The degradation of [carbonyl - 14C] - cis, trans-permethrin was studied in Dubbs fine sandy loam soil incubated at 10, 25, and 40 degrees C from 0 to 64 days. The most rapid degradation of permethrin to [carbonyl - 14C] - cis, trans -3- (2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (DCVA) and ultimately 14CO2 occurred at 25 degrees C. Rapid degradation to DCVA also occurred at 40 degrees C, however, further degradation of DCVA to 14CO2 was reduced. Permethrin degradation to 14CO2 was slowest at 10 degrees C. The degradation rate of trans-permethrin was greater than the cis-permethrin at all temperatures tested. The halflives of cis- and trans-permethrin were 55 and 14 days at 10 degrees C, 12 and 5 days at 25 degrees C, and 27 and 4 days at 40 degrees C, respectively. Compounds identified from treated soil were the original [carbonyl - 14C]-cis, trans-permethrin and the major degradation products cis-, and trans-DCVA.