The relationships between serum corticosterone content, intensity of lipid peroxidation (LPO) and the concentration of tocopherol in tissues, and the transmembrane potential in thymocytes were studied in rats exposed to two consecutive coolings. Both exposures increased serum corticosterone. The first exposure activated LPO in the serum, while the second stimulated LPO in thymocytes. The second cooling lowered body temperature to a lesser extent than the first one. Body temperature did not depend on the content of LPO products or corticosterone, but negatively correlated with the content of tocopherol in the brain hemispheres and adrenal glands. The rats exhibiting high-level thermoregulation after the first exposure to cold showed a higher thymocyte transmembrane potential after the second cooling. The second exposure potentiated the negative relationship between the brain and serum content of corticosterone and LPO products, which indicates that the content of LPO products cannot be used as an index of stress intensity.