In early chronic atrophic gastritis there appear patches of altered surface epithelium having the morphologic and histochemical characteristics of a regenerating mucosa. This suggests that prior injury to the neck and crypt areas of the normal gastric surface epithelium may have pathogenetic significance in the onset of this disease. The appearance of numerous enzymes and acidic glycoprotein in intestinalized mucosa within the stomach suggest that this new epithelium has acquired properties not found in normal gastric surface epithelium. The decreased numbers of chief and parietal cells in chronic atrophic gastritis cannot be explained by accelerated destruction of these cells or by excess shedding of them into the gastric lumen.