Three experiments involving 106 weanling pigs were conducted to determine the effect of various additives to swine diets which contained ulcerogenic gelatinized corn. A fourth experiment using 72 male albino rats was conducted in an attempt to induce esophagogastric ulcers in the rat. All animals were fed a gelatinized corn-soybean meal basal ration, and treatments consisted of additions of various additives to this basal ration. It was hypothesized that the basal ration would induce a high incidence of esophagogastric ulcers in swine and that one or more treatment additives would reduce the incidence of the ulcer. Pigs were slaughtered at 200 lb. or at 125 lb. live weight. Ulcers, erosions, or cornification of the esophageal region of stomachs were not prevented by oxytetracycline, oxytetracycline+CuSO4, 2,000 or 5,000 I.U. of vitamin A per pound, tocopherol, tocopherol acetate, menadione, methionine, an amylolytic-proteolytic enzyme, librium hydrochloride tranquilizer, an antihistamine, or distillers dried solubles. A total of 35 ulcers (33.3%) occurred with seven deaths resulting from the ulcers. The incidence of esophagogastric cornification was 100% in almost all treatments, and erosions ranged from 50 to 100%. Hemoglobin and hematocrit studies indicate that these are unreliable criteria for detecting chronic esophagogastric ulcers. Vitamin A of the plasma and liver stores of vitamin A at slaughter indicated that no interference of vitamin A absorption was present. Blood was noted in the feces of some affected pigs. Esophagogastric ulcers were not induced in rats fed the same gelatinized corn diets that were ulcerogenic to swine.