The effects of adrenalin on phosphate metabolism in the seminal vesicles were reported. Adrenalin was administrated into rabbit's seminal vesicles comparing to the intramuscular injection. Experiments were performed in two ways, one was only single administration and the other was continuous for 10 days and the results were as followed. 1. By the administration of adrenalin into the seminal vesicles and intramuscular, RNA was increased, whereas DNA showed mostly the same level as in normal condition. 2. RNA was gradually decreased as well as in DNA after the castration. 3. On the effects of adrenalectomy, no significant effects could be seen in RNA and DNA by adrenalin administration in seminal vesicles with cortisone therapy, whereas with no cortisone therapy, valuable changes could be seen in RNA and DNA levels. 4. Comparing the effects of adrenalin on phosphate metabolism in seminal vesicles with muscle, the effects were essentially the same on both tissues, although much stronger reactions could be found in muscle than the seminal vesicles.