New knowledge about accidental hypothermia acquired in recent years may simplify treatment and aid the evaluation of prognosis. Evidence of death or severe collapse due to the feared afterdrop has not been published. Afterdrop is a phenomenon of conductive heat loss. Evaluation of rewarming techniques shows that results from forced air rewarming techniques are equivalent to or better than results from invasive rewarming methods, except for rewarming with cardiopulmonary bypass. In hypothermia the most important differential diagnosis is death. Patients who are cold and could be resuscitated must be differentiated from patients, who are cold because they are dead. Experience from abroad has shown that extreme hyperkalaemia may be a useful diagnostic tool.