This contract is in support of the United State Renal Data System (USRDS) national registry. The USRDS is a longitudinal registry of all persons in the US who have end stage renal disease (ESRD). This includes all persons on dialysis and recipients of kidney transplantation. The data base is inclusive of all incident cases of ESRD from 1980 to the present. Information on ESRD patients include date and cause of renal failure as well as co-morbid conditions. In addition, follow-up data include mortality, hospitalization and other indicators of morbidity and disability, as well as expenditure data. In addition, the USRDS includes similar information on persons with chronic kidney disease.