This report presents the findings of the first-ever international assessment of the environmental impact of depleted uranium (DU) when used in a real conflict situation. Following the confirmation by NATO that DU had been used during the Kosovo conflict, the United Nations Environment Program organized a scientific field mission to investigate the possible environmental consequences. This report presents its findings and conclusions on the presence and extent of DU contamination at the areas studied, the corresponding risks to the environment, and possible mitigation actions.