Hypothermia is defined as a core body temperature less than 35 degrees C (95 degrees F) and results from prolonged exposure to cold environment, drugs, and underlying pathologic conditions. Hypothermia is associated with marked depression of cerebral blood flow and oxygen requirement, reduced cardiac output, and decreased arterial pressure. Victims can appear to be clinically dead because of marked depression of brain and cardiovascular function, bet full resuscitation with intact neurological recovery is possible. Alcohol or drug intoxication are the dominant precipitating factors. There are about 20,000 hypothermia--related deaths a year in Britain, about 25,000--in the USA, 8,000 deaths a year in Canada. There are suggestions that the unofficial number of hypothermia--related deaths is substantially higher, particularity in the elderly. This article reviews the cause, pathogenesis, pathophysiology, clinical features, electrocardiographic manifestations of hypothermia, diagnosis, pre-hospital stabilization, hospital passive, active external, active core rewarming methods, other questions of treatment, and mortality of hypothermia. It is very important to remember, thar if a hypothermic victim is alive when rescued but dies during recovery treatment, and there is no other significant trauma or disease, this suggests that death may have resulted from either inappropriate or ineffective treatment, or no treatment at all.