Mineralization of aldicarb to C02 as well as formation of various metabolites and extractable and nonextractable 14C were measured in [14C] aldicarb-treated surface and subsurface soils. Surface soil samples were incubated under aerobic conditions, and subsurface soil samples were incubated under aerobic and anaerobic conditions. Total aldicarb, aldicarb sulfoxide, and aldicarb sulfone residue (TTR = total toxic residue) disappearance rates were also determined in soils held under aerobic conditions. These data were used to compute half-lives for aldicarb mineralization and TTR disappearance in soil. TTR disappearance in soils held under strict anaerobic conditions, despite slow mineralization, was more rapid than under aerobic conditions. Mineralization rates for surface soil samples were generally higher than for subsurface soil samples. Metabolites detected included aldicarb sulfoxide, aldicarb sulfone, aldicarb sulfoxide oxime, aldicarb sulfoxide nitrile, aldicarb sulfone oxime, TLC polar products, and two unknowns. Aldicarb sulfone and its hydrolysis products were not detected in soils incubated under