1. In hydrated rats the rate of water excretion increased on exposure to cold. Antidiuretic effect of Pitressin was significantly diminished in a cold atmosphere.2. In hydrated rats administrations of epinephrine, norepinephrine and hydrocortisone resulted in an increase of urinary excretion of water and countervailed antidiuretic effect of Pitressin. ACTH showed similar effect. DOCA and cortisone were without effect.3. In adrenalectomized and hypophysectomized rats cold exposure did not cause any increase in water excretion, while adrenal demedullated rats and thyroidectomized rats showed an increased water excretion on exposure to cold.4. It was concluded that the secretion of the adrenal cortex participates in bringing about the increased water elimination on exposure to cold.