Abstract: Mild hypothermia significantly increases perioperative complications, such as adverse myocardial outcomes, coagulopathy, infection and delayed recovery. So it is important to maintain the core temperature above 36℃. Redistribution is the major cause of hypothermia during the first hour of intravertebral or general anesthesia. There are many methods to protect patients from hypothermia including passive insulation and active warming. Forced-air and electric heating pad are currently the most effective noninvasive choices. The contribution of intravenous fluids heating to patients' temperature is limited but it should be performed when large volumes are required.