High and low temperatures, physical exercises and acute hypoxia are studied for their effect on indices of peroxide lipid oxidation in highly trained persons under alpine conditions (2100-5600 m). Temperature effects (-15 degrees C and +100 degrees C, for 30 minutes) as well as their combination with acute hypoxy cause an increase (by 10-30%) of malonic dialdehyde and a decrease (by 46-70%) of spontaneous chemoluminescence of blood serum in nonadapted people. Adaptation to alpine conditions in combination with physical exercises and low-caloric diet decreases shifts of these indices, considerably increasing the organism stability to the action of such extreme stress agents as high and low temperatures and acute hypoxy.