Several studies have been conducted to investigate the fate of atrazine (ATR, 2-chloro-4[ethylamino]-6[isopropylamino]-s-triazine) and major degradation products of ATR in soils of Iowa by using laboratory radiotracer studies, field lysimeters, and a field-scale approach. Complete metabolism studies of uniformly ring-labeled 14C-chemicals revealed some major trends. Persistence of ATR, deethylatrazine (DEA, 2-chloro-4[amino]-6[isopropylamino]-s-triazine), and deisopropylatrazine (DIA, 2-chloro-4[ethylamino]-6[amino]-s-triazine) was greater in subsurface soils than in surface soils. In surface soil of Ames, DEA and didealkylatrazine (DDA, 2-chloro-4,6-[diamino]-s-triazine) were predominant degradates of ATR after 60 d, and hydroxyatrazine (HYA, 2-hydroxy-4[ethylamino]-6[isopropylamino]-s-triazine) was the predominant degradate of ATR after 180 d. The persistence of ATR, DEA, and DIA was significantly reduced under saturated soil moisture conditions than in soils held at a moisture near field capacity. Relative mobilities of ATR and degradates in five Iowa soils (surface and subsurface), determined by soil thin-layer chromatography, indicate that DEA is more mobile than ATR. The relative mobilities of DIA, DDA, and ATR were similar. Also, laboratory studies with undisturbed soil columns are supportive of greater mobility of DEA than ATR. In a field-scale study investigating the mobility of ATR and its degradates, it was indicated that ATR degradation products by themselves, or in combination with the parent compound can exceed the maximum contaminant level (MCL) of 3 µg/L currently set for ATR alone. In ATR-applied field plots, DEA and DIA were detected along with ATR in tile drain water samples, with concentrations of DEA exceeding DIA. In Extrazine®- (a herbicide mixture of 67% cyanazine [CYA; 2-chloro-4-ethylamino-6-(1-cyano-1 methylethylamino)-s-triazine] and 21% ATR) -applied field lysimeters, the concentrations of DIA exceeded those of DEA.