Public health policies such as tobacco control, air pollution reduction, and hazardous waste remediation may have reduced cadmium exposure among U.S. adults. However, trends in urine cadmium, a marker of cumulative cadmium exposure, have not been evaluated. The authors estimated the trends in urine cadmium concentrations in U.S. adults using data from the National Health and Nutrition Examination Surveys (NHANES) from 1988 to 2008.