Stomach ulcers of various stages occurred in seven adult male Syrian golden hamsters fed on a vitamin A-free diet for seven months. The ulcers were located in the glandular portion close to the forestomach. These hamsters showed food retention containing various amounts of hair in the stomach. Histopathologically, the early ulcerogenic change was focal necrosis of the glandular epithelium, which resulted in erosion and ulcer, with leukocytic infiltration and edema of the surrounding tissue. The most advanced ulcers exhibited perforation of the gastric wall resulting in adhesive peritonitis. In an additional experiment in .that hamsters were fed on a diet mixed with their own hair, no gastric food retention nor morphological alterations of the glandular stomach were observed. It was suggested that the induction of stomach ulcers might be a synergistic effect of the necrotic changes in the glandular epithelium and the food retention caused by vitamin A-deficiency state.