Despite skilled palliative care, some dying patients experience distressing symptoms that cannot be adequately relieved. A patient with metastatic breast cancer, receiving high doses of opioids administered to relieve pain, developed myoclonus. After other approaches proved ineffective, palliative sedation was an option of last resort. The doctrine of double effect, the traditional justification for palliative sedation, permits physicians to provide high doses of opioids and sedatives to relieve suffering, provided that the intention is not to cause the patient's death and that certain other conditions are met. Such high doses are permissible even if the risk of hastening death is foreseen. Because intention plays a key role in this doctrine, clinicians must understand and document which actions are consistent with an intention to relieve symptoms rather than to hasten death. The patient or family should agree with plans for palliative sedation. The attending physician needs to explain to them, as well as to the medical and nursing staff, the details of care and the justification for palliative sedation. Because cases involving palliative sedation are emotionally stressful, the patient, family, and health care workers can all benefit from talking about the complex medical, ethical, and emotional issues they raise.