Gastric ulcers in 243 patients, all of whom were 50 years of age or older, were studied by autopsy procedures, and the data were correlated with some of the presumptive factors in the differential diagnosis of gastric ulcer. The teaching that the benign types of ulcer occur more commonly than those of neoplastic origin was upheld; a 3-to-1 ratio was found to exist and to extend to the 80-year-old group of patients. Classification of ulcers by size and type gave the following information: 10% of the benign ulcers were 4 cm. or more in diameter and 20% of the malignant ulcers were 2 cm. or less in diameter, but in the 53 ulcers larger than 4 cm. the number (33) of neoplasms was greater. No differential diagnostic values could be assigned to the location of the ulcer on the stomach wall. Transformation from a benign to malignant lesion was calculated to take place in less than 1 % of peptic ulcers.