Atmospheric transport and deposition of pesticides are significant issues in better understanding human and environmental exposure. Pesticide concentrations in air and precipitation were measured over a one-year-period at four sites in Iowa chosen to characterize rural, urban and regional effects. Twenty-eight pesticides including twenty-one herbicides and seven insecticides were detected in precipitation during the sampling period, October 1996 through September 1997. Pesticide concentrations were greatest during the planting-growing season, April through August. Peak concentrations reached 0.96 ug/L for acetochlor, 1.1 ug/L for 2,4-D, and 3.5 ug/L for atrazine, all commonly used herbicides in Iowa. Concentrations were generally higher at the farm site but were present at all sites indicating distant transport. Measurable air concentrations were occasionally seen, but most were below detection limit for the volume of air sampled.