The case of Terri Schiavo resulted in substantial media attention about the use of artificial nutrition and hydration (ANH) especially by percutaneous endoscopic gastrostomy (PEG). In this article, I review ethical and legal principles governing decisions to choose or forgo ANH at the end of life, including issues of autonomy and decision-making capacity, similarities and differences between ANH and other medical treatments, the role of proxies when patients lack decision-making capacity, and the equivalence of withholding and withdrawing treatment. Evidence for palliative or life-sustaining benefits for ANH are reviewed in three disease processes: amyotrophic lateral sclerosis (ALS), cancer, and dementias, including Alzheimer's disease. Although more recent studies suggest a possible palliative role for ANH in ALS and terminal cancer, feeding tubes do not appear to prolong survival or increase comfort in advanced dementia of the Alzheimer's type.