Health-care insurance is the key to health-care access, yet the number of uninsured in the United States grows by a million persons per year and consists, in large part, of those who are financially unable to obtain medical coverage. Their unpaid medical bills add significantly to the cost of health insurance for those who do pay. Those without insurance receive care on a sporadic basis, and the risk of poor health-care outcomes is well established. The end-stage renal disease (ESRD) uninsured face unique problems related to chronicity of care and the system of chronic dialysis-care delivery. This article addresses the growing challenge of the ESRD uninsured in the United States and describes how the current system copes with the ESRD uninsured. More broadly, it discusses who the uninsured are (including undocumented immigrants), the health-care consequences of being without coverage, and how their care is currently financed. It also presents a health-care reform measure in Massachusetts designed to provide affordable insurance to those without coverage.