Effect of cold exposure on aggressive behavior, on the concentrations of testosterone and glucocorticoids, as well as on the oxygen consumption at different ambient temperatures, and calorigenic effect of noradrenaline have been studied in BALB/cLac and C57Bl/6J males. Under normal temperature conditions, there have been no significant interstrain differences. After cold exposure (5 weeks at 6-8 degrees C), C57Bl/6J mice exhibited more pronounced adaptive changes in thermoregulation and endocrine status (increase of glucocorticoids and decrease of testosterone concentrations were less expressed in C57Bl/6J than in BALB/cLac). At the same time, males of this strain demonstrated more intensive aggression than BALB/cLac mice. Some relations between physiological and behavioral changes caused by cold exposure are discussed.