In this paper, we review ethical issues that arise when families and doctors face clinical decisions about renal replacement therapy for an infant with end-stage renal disease (ESRD). Over the last 20 years, many centers have begun to routinely offer renal replacement therapy. However, doctors and nurses both continue to view such therapy as optional, rather than mandatory. We speculate that the burdens of therapy on the family, and the uncertainties about satisfactory outcomes have led to a situation in which renal replacement therapy remains desirable, but non-obligatory. We discuss the reasons why this is likely to remain so, and the ways in which renal replacement therapy for infants with ESRD is similar to, or different from, other clinical situations in pediatrics. Finally, we propose a research agenda to answer questions that are crucial to making good ethical decisions about infant dialysis.