Insecticide residues on suspended and bottom sediments of streams of Ontario, Canada, were studied in a tobacco-growing and a vegetable muck area. The proportion of TDE [2,2-bis(p-chlorophenyl)-1,1-dichloroethane] of DDT was < 1 in water and > 1 in bottom sediments. The ratio of TDE to DDT in bottom material increased linearly from the contamination point at stream source to the mouth of Big Creek in Norfolk Country, Ontario. Bed load samples contained 3-6 times greater concentrations of insecticides than bottom material. Adsorption of insecticides on suspended sediment decreased in order DDT > TDE > dieldrin > diazinon, which is consistent with the water solubility of these compounds.