The mucosa of the gastric remnant of 41 subjects who had been operated upon 17-18 years earlier for peptic ulcer was studied histologically. The histological changes were classified as follows: 1) normal mucosa, 1; 2) simple gastritis, superficial or atrophic, 27; and 3) "selective loss of parietal cells", 13 subjects. The latter type was characterized by marked loss of parietal cells without corresponding loss of other epithelial elements and without an inflammatory reaction. These changes were thought to reflect a lack of a trophic action on parietal cells exerted by gastrointestinal hormones, as e.g. gastrins.