While many studies have estimated the impacts of air pollution on crop yields on experimental plots, few have estimated these impacts under actual farm production conditions. This study econometrically estimates the impact of air pollution on corn and soybean yields, controlling for weather, soil quality and management practices, using farm-level data for the eastern United States. Ozone pollution was found to reduce yields for both crops. The mean elasticity of yield with respect to ozone exposure was -0.19 for corn and -0.54 for soybeans. The benefits of ozone standards to protect crops, measured in terms of crop revenues, range from $17 to $82 million depending on the stringency of the standard. Over 85 percent of the revenue gains are captured by three states: Maryland, North Carolina, and Virginia.