The constancy of body temperature (CBT) is a cornerstone of homeostatic, homothermic organisms and is essential for a regulated course of biochemical and biophysical reactions. Severe deviations from normothermia (36.8+/-0.4 degrees C) are life threatening and even a moderate perioperative reduction of the CBT is coupled with an increased morbidity and mortality especially in high-risk patients. The relevant factors are coagulation disturbances, increased infection rate and increased cardiac risk. Normothermia should be achieved by the consistent use of warmth-conserving measures. On the other hand, a deliberate reduction in temperature or induced hypothermia is a neuroprotective procedure, which offers a therapeutic option to minimize neuronal secondary damage after primary hypoxic-ischemic events as well as extending the neuronal tolerance to ischemia. Management includes the practice of cooling down to a defined temperature, rewarming as well as a differentiated control of various parameters. Furthermore, side-effects which increase in severity with decreasing temperature must be taken into consideration.