SummaryThe authors review 39 cases of adult patients with accidental hypothermia. The frequency of this affection is presumably higher than generally thought, especially in normal but aged patients and in different pathological conditions which interfere with the mechanisms of thermoregulation. Eventhough the diagnosis of hypothermia is a simple one, it is probably often missed because the symptoms of the causal disease are frequently masking it, but also because the characteristic signs of hypothermia appear only when the temperature is really low (under 33°C).Clinical manifestations of hypothermia are quite various and are largely depending on the causal disease. Shivering, muscular hypertonia, skin modifications, hemodynamic disturbances, bradycardia and bradypnea are usually observed. The authors underline the possible absence of severe alterations of conscience, even when the central temperature reaches 26°C. Biological tests are generally slightly perturbed.The prognosis is closely related to the prognosis of the causal disease. The major complications are hypotension, cardiac arrhythmias, infectious bronchopulmonary complications. Intensive therapy (active or passive rewarming, maintenance of a good circulatory state, artificial ventilation if necessary) and a constant watching of these patients in an intensive care unit are a necessity. In these conditions, and providing that the causal affection is reversible, the prognosis of hypothermia is good, even if the central temperature is deeply lowered.