Palliative sedation (PS) is the use of medications to induce decreased or absent awareness in order to relieve otherwise intractable suffering at the end of life. Although uncommon, some patients undergoing aggressive symptom control measures still have severe suffering from underlying disease or therapy-related adverse effects. In these circumstances, use of PS is considered. Although the goal is to provide relief in an ethically acceptable way to the patient, family, and health care team, health care professionals often voice concerns whether such treatment is necessary or whether such treatment equates to physician-assisted suicide or euthanasia. In this review, we frame clinical scenarios in which PS may be considered, summarize the ethical underpinnings of the practice, and further differentiate PS from other forms of end-of-life care, including withholding and/or withdrawing life-sustaining therapy and physician-assisted suicide and euthanasia. © 2010 Mayo Foundation for Medical Education and Research.