The author presents a review of changes in thermoregulation in various ages. The changes at infant and older ages are compared in contrast to thermoregulation in healthy adults. Hypothermia occurs in all age groups, especially in the aged. Then it is determined by both low temperature of environment and impairment in production and expenditure of heat despite the normal environment temperature. A special form of hypothermia is represented by intraoperative hypothermia in the course of surgical performance under general anaesthesia. Hyperthermia occurs most frequently as heatstroke in consequence of high environmental temperature. The author presents etiopathogenesis and pathomechanisms, possible treatment and prevention in thermoregulation disturbances. (Tab. 6, Ref. 79.).