Assessments of air pollution impacts on crops may overestimate losses because they do not consider the impacts of soil moisture deficits on pollutant uptake by plants. A recent model of moisture stress X ozone interactions predicted reduced ozone impacts on yields of drought-stressed crops, due in part to an assumed reduction in the ozone damage during drought. The paper describes an evaluation of the model with ozone X moisture stress field experiments on soybean conducted at Raleigh, NC, U.S.A. Modelled yield losses due to ozone were smaller than observed for moisture-stressed soybean, but these differences were not statistically significant. The model predictions were consistent with the ozone X H2O interaction observed by other researchers for soybean grown in a controlled environment. (Copyright (c) 1988 Elsevier Science Publishers B.V.)