Background: Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. The noninvasive assessment of such damage, i.e., in urine, and application to large-scale human studies are vital to understanding this role and devising intervention strategies. Methods: We have reviewed the literature to establish the status quo with regard to the methods and meaning of measuring DNA oxidation products in urine. Results: Most of the literature focus upon 8-oxo-7,8-dihydro-2 ¶-deoxyguanosine (8-oxodG), and whereas a large number of these reports concern clinical conditions, there remains (a) lack of consensus between methods, (b) possible contribution from diet and/or cell death, (c) no definitive DNA repair source of urinary 2 ¶-deoxyribonucleoside lesions, and (d) no reference ranges for healthy or diseased individuals. Conclusions: The origin of 8-oxodG is not identified; however, recent cell culture studies suggest that the