The relationship between the ulceration in the glandular stomach of rats, induced by adranalectomy, and the substitution therapy or the changes in blood components has been investigated. As agents for the substitution therapy after adranalectomy physiologic saline solution, cortisone and DOCA were used. During the substitution therapy, non-protein nitrogen in whole blood, protein and sodium-potagsium concentration in serum were determined. When the abnormality of sodium-potassium balance in the serum after adrenalectomy was corrected by the administration of physiologic saline solution or cortisone (0.1-0.15/mg/day/100g B.W.), ulceration could be prevented. However, when the excessive substitution therapy by cortisone (5 mg/bay/animal) was done, it was failed to prevent the induction of ulceration. When DOCA was used excessively and sodium-potassium balance in serum was under the state of disharmony, no ulceration was found. And it was recognized that the ulceration and the change in the none protein nitrogen or protein was not intimately correlated. Through these experiments, it has been, therefore, surmized that the gastric ulceration following adranalectomy was mainly influenced by the sort of substitution therapy, rather than by the alteration of certain specific factor in the blood components.