Carbofuran (2,2-dihydro-2,2-dimethyl-7-benzofuranylmethyl-carbamate) is a broad spectrum insecticide which is effective against soil insects in corn, rice, sugar cane, peanuts, cotton and pests on potatoes. Decreased effectiveness of insect control in soils treated with carbofuran was observed after soils had been treated for a number of years. Loss of efficacy was not related to insect resistance or soil leaching. Irreversible adsorption was not involved; however, the carbofuran levels in the soil were lower than expected. Repeated applications of carbofuran increased the rate of degradation. The objective of these experiments was to study the potential of enhanced /sup 14/C-carbofuran degradation in two South Carolina soils which had been treated for several successive years. The degree of degradation and type of degradation products were also determined.