This chapter describes the methods currently in general use to assess uranium concentrations in tissues resulting from exposure to depleted uranium (DU) in environmental media, and the resulting radiation doses. Because of the importance of inhalation of airborne dust in such assessments, it includes an introduction to the mechanisms and terminology relating to aerosols. Much of this chapter is based on material prepared by the authors for ICRP publications relating to intakes of radio-nuclides, especially the ICRP Guide for the practical application of the ICRP human respiratory tract model (2002), and in support of the Royal Society (2001, 2002) assessments (Bailey and Phipps, 2002; Bailey, 2002a, 2002b), and reproduced here by kind permission of the ICRP and the Royal Society.