This report is a summary of the discussion on the United States Renal Data System and its data contents, as presented at the Symposium on World Renal Registries on December 10, 1993. The United States Rental Data System is a national database that collects and analyzes information on the incidence, prevalence, morbidity, and mortality, as well as the modalities of therapy of patients with end-stage renal disease (ESRD) in the United States. The database is funded by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health. Data on the patients are provided by the Health Care Financing Administration Medicare Program. The coordinating center for the database, operated through a contract mechanism, was formerly at the Urban Institute in Washington, DC, but is currently located at the University of Michigan, Ann Arbor, MI. The data system contains information on over 462,000 patients with more than 4 million dialysis records, 2.3 million inpatient records, 94,000 transplant reports, and more than 290,000 follow-up reports. The incidence rate of ESRD is approximately 180 per million population. However, the rate is higher in African-Americans (430) and Native Americans (281) than in whites (153) and Asian/Pacific Islanders (133). The gross mortality rate of the entire ESRD population is approximately 168 deaths per 1,000 patient-years at risk. The death rate is higher in diabetic than in nondiabetic ESRD patients. It is also higher in ESRD patients older than 65 years (357) than in patients in the 45- to 64-year-old age group (158) or those in the 20- to 44-year-old age group (62).