A written advance directive (AD) is a document intended to indicate a person's preferences with respect to treatment decisions that may be necessary if and when that person becomes incompetent. Both in research and in practice, there are features of the dialysis population that make ADs potentially quite relevant and useful. An evolving body of empiric literature supports the use of these documents in this unique population. This article reviews this literature, discusses the philosophic foundations and legal status of ADs, provides some pilot data on a dialysis-specific living will being developed at the University of Toronto Centre for Bioethics, examines clinical considerations related to ADs, and finally suggests future research directions.