Used for over 3600 years,hypothermia,or targeted temperature management(TTM),remains an ill defined medical therapy.Currently,the strongest evidence for TTM in adults are for out-of-hospital ventricular tachycardia/ventricular fibrillation cardiac arrest,intracerebral pressure control,and normothermia in the neurocritical care population.Even in these disease processes,a number of questions exist.Data on disease specific therapeutic markers,therapeutic depth and duration,and prognostication are limited.Despite ample experimental data,clinical evidence for stroke,refractory status epilepticus,hepatic encephalopathy,and intensive care unit is only at the safety and proof-of-concept stage.This review explores the deleterious nature of fever,the theoretical role of TTM in the critically ill,and summarizes the clinical evidence for TTM in adults.