The end-stage renal disease (ESRD) program is the only Medicare program for which entitlement is based on the presence of a medical diagnosis. In addition, entitlement is nearly universal. Over 90% of persons with ESRD receive Medicare benefits. Because of these unique characteristics, the ESRD program has been the subject of continuing debates about the role of the Federal government in the categorical funding of high-cost illnesses, reimbursement policies, and the ethical issues of treatment of terminal, or near terminal, patients. This report presents descriptive data from the Medicare ESRD Program Management and Medical Information System (PMMIS) concerning trends in program expenditures, incidence and prevalence of ESRD, and mortality. The purpose is to provide background material for informed discussions of these issues. Expenditures for the ESRD program have grown from $240 million in 1974 to $3.3 billion in 1987. During that same time, total Medicare expenditures increased at a comparable rate so that ESRD costs have remained a relatively constant proportion of Medicare costs for the last decade. The ESRD population is rapidly changing. Between 1978 and 1987, enrollment nearly tripled, from 44,000 to 124,000. Much of this change has occurred in the elderly population. Persons over 65 accounted for 20% of total enrollment in 1978 and 29% of total enrollment in 1987. Census projections show that the "graying" of the ESRD population will continue into the foreseeable future. Transplantation has had a marked effect on the ESRD population. Persons with a functioning kidney graft have increased from 11% of the total population in 1978 to 22% in 1987.(ABSTRACT TRUNCATED AT 250 WORDS)