In medicine, triage () is a practice invoked when acute care cannot be provided due to a lack of resources. The process rations care towards those who are most in need of immediate care, and who will benefit most from it. More generally it refers to prioritisation of medical care as a whole. In its acute form it is most often required on the battlefield, during a pandemic, or at peacetime when an accident results in a mass casualty which swamps nearby healthcare facilities' capacity.

Triage always follows the modern interpretation of the Hippocratic oath, but otherwise there is plenty of leeway in interpretation, leading to more than one simultaneous idea of its nature. The best-settled theories and practical scoring systems used come from the area of acute physical trauma in an emergency room setting; a broken bone obviously counts for less than uncontrolled arterial bleeding, which is likely to lead to death. But no current principle carries over well to mental health, reproductive health (such as abortion), chronic medical conditions, geriatrics, or palliative care (including euthanasia). This is because triage needs to balance multiple and sometimes contradictory objectives simultaneously, most of them being fundamental to personhood: likelihood of death, efficacy of treatment, patients' remaining lifespan, ethics and religion.