Twenty-four female rats were randomly divided into 2 groups. One group was placed in a cold room at 5-7cC. The other group remained at room temperature, 25-27[degree]C. After a period of 3-5 weeks the rats were sacrificed. liver, kidney, heart and brain weights were recorded and the epinephrine and norepinephrine content of the adrenal, heart and brain determined by the fluorimetric method. Exposure of female rats to temperatures of 5-7[degree]C for 3r5 weeks resulted in a hypertrophy of the liver, heart and kidney. The catechololamine content of the brains of these animals was unchanged, while the heart was significantly reduced and the adrenal content significantly increased.