The effect of an ambient temperature of 2° C upon the weight of mouse adrenal glands was investigated after 4, 15, 30 and 45 days of exposure. A general increase in adrenal gland weight was found to occur for each of the four exposure periods with significant increases occurring on the fifteenth and forty-fifth days of exposure. The increase noted on the fifteenth day resulted from the response of the male adrenal glands and that on the forty-fifth day was found to be produced by the response of the female adrenal glands. The rapid increase in adrenal gland weight of the male relative to the female is suggestive of a homeostatic mechanism functioning perhaps as a facet of the adaptive stage of the general alarm reaction to stress. Weights of thymus glands in cold exposed mice were essentially unchanged. Comparison of the thymic gland weight and the adrenal gland weight of the cold exposed mice revealed no relationship between an increase in adrenal gland weight and a decrease in thymus gland weight. The significance of this observation is not apparent but may be considered to reflect the unique nature of low temperatures as a stressing agent.