The experiments were carried out on male Wistar rats administering the tested catecholamines intraperitoneally. Water for diuresis induction and indomethacin solutions were introduced into the stomach through a tube. The hypophysis was destroyed totally with a needle inserted into an ear under stereotaxic controls. Lower adrenaline doses increased water diuresis, higher doses decreased it. Noradrenaline exerted only in antidiuretic effect. There was an analogy between the effects of these amines in diuresis and on adrenergic receptors. Hypophysectomy increased the antidiuretic action of adrenaline which could be due to absence of ACTH. Lower doses of indomethacin inhibited and higher doses enhanced the antidiuretic effect of amines. Intermediate doses were ineffective.