Biochemical analysis of acid mucosubstances was carried out on the mucosa of the fundus and pylorus of control rats after a short treatment with ACTH or cortisone. After hormonal treatment, an increase in the total content of acid mucosubstances and distinct changes in the ratios of amino sugars, uronic acids and sulfated polysaccharides were observed. The changes found in the pyloric mucosa were more significant than those in the fundus.