The application of managed care to dialysis raises concerns that dialysis will be rationed in the United States. Rationing means the implicit or explicit denial of beneficial or marginally beneficial medical treatment as a result of insufficient resources to provide treatment to all. In this era of cost containment and budget cutting, rationing appears inevitable in the end-stage renal disease program because of its continued growth in numbers and cost and because many are questioning the benefit of dialysis to certain groups of patients. Rationing according to social worth, ability to pay, or age is not ethically justifiable, but it is justified to ration according to medical benefit. There is an important role for guidelines developed with broad input from patients, families, health care professionals, ethicists, health policy experts, and payers. Consensus statements exist in the literature, and the nephrology community is in the process of developing practice guidelines that will be available for future use. In the meantime, managed care companies should look to broader community input in the form of consensus statements and community dialogue. Managed care companies will need ethics committees to ensure that their policies and procedures for rationing are fair, principled, and subject to review and appeal.