This study was designed to reappraise the distribution pattern of gastrin-producing cells (G cells) in the human stomach bearing chronic peptic ulcer and carcioma. Of a total of 40 gastrectomy specimens (8 gastric ulcers, 11 duodenal ulcers and 21 gastric carcinomas), ten stomachs were processed by full mapping of the whole gastric mucosa, and the remaining 30 stomachs were studied using a lesser curvature strip method. G cells were stained using peroxidase-antiperoxidase against human gastrin, and their population densities were evaluated with morphometric and histotopographic analyses. The followings are summary of the result. 1) G cells were mainly located at the basal portion of the pyloric gland area, exclusively in the foveolar linings. They were reduced in the area with intestinal metaplasia. The mean diameter of the G cell nuclei was 6.26 pm. 2) The mean number of total G cells in a stomach was estimated 32.67 millions in gastric cancer cases and 99.02 millions in duodenal ulcer cases. This difference was statistically significant (p<0. 001). 3) The number of total G cell population decreased gradually with increasing age in both groups. 4) The G cells were fewer in the lesser curvature than in the anterior or posterior wall 5) The G cell population remained relatively even from the pyloric ring to the portion 3cm proximal to the duodenum The gastric angle portion contained the least number of G cells than the distal portions 6) The G cell number in the lesser curvature strip was highest in the duodenal ulcer cases and lowest in the gastric cancer patients, while the number of G cell varied considerably in cases with gastric ulcer The above findings support that the G cell hyperplasia is involved in the pathogenesis of peptic ulcer disease.