Key summary pointsAimThis systematic review provides an overview of existing literature on the incidences of underlying causes of hypothermia in older patients at the emergency department.FindingsUnderlying causes of hypothermia that should not be missed include infectious, endocrine, neurological, cardiac and gastro-intestinal diseases, trauma, alcohol intoxication, primary hypothermia, and drug-induced hypothermia.MessageKnowledge of the a priori chances of underlying causes of hypothermia in older patients presenting to the emergency department may affect initial management, hence prognosis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s41999-023-00791-0.