Thirty-six cases of human atrophic chronic gastritis were observed by transmission and scanning electron microscope. Generally, in the surface and neck mucous cells, vacuole formations and swelling of mitochondria were occasionally observed. Although, increase of young parietal cells were frequently noted, ultrastructural changes were hardly seen in the cytoplasm and the nucleus of both the parietal cells and the chief cells. Intestinal metaplastic mucosa was found in almost all cases of antral mucosa and in half cases of corporal mucosa of chronic gastritis. In the SEM observation, the gastric mucosa and the intestinal metaplastic mucosa were clearly bordered. In TEM observations, all types of normal small intestinal cells were found in the intestinal metaplastic mucosa, and there were no ultrastructural differences between normal intestinal cells and intestinal metaplastic mucosa cells. It was interesting that enterochromaffin cells, which were scarce in normal gastric mucosa and numerous in small intestine, were frequently observed in intestinal metaplastic mucosa. In the three cases of chronic gastritis, the peculiar type cells which had both endocrine cells granules and mucous granules were found and their origins were discussed.