The relationship between chronic gastritis and peptic ulcer was studied in 97 patients, 51 with duodenal ulcer and 46 with gastric ulcer. Six biopsies (three from the antrum and three from the body) were obtained under direct vision by means of an Olympus panendoscope. Chronic gastritis was classified according to the grade of inflammation (slight or moderate and intense), and to its location (antritis or pangastritis). In gastric ulcer the relationship between frequency of chronic gastritis and the site of the ulcer (antrapyloric, at the angulus, body of the stomach) was also established. Antritis was just as frequently observed in duodenal ulcer (94%) as in gastric patients (96%), but severe inflammation of the antrum was higher in G.U. (43%) than in D.U. (17%). Chronic gastritis of the gastric body was always accompanied by antritis, both in G.U. and in D.U. and was observed in 63% of the former group and 37% of the latter. Severe inflammation of the glandular portion of the stomach occurred in only one patient with D.U (2%) and in 7 with G. U (15%). In the present investigation, no relationship between between the site of gastric ulcer and the frequency of chronic gastritis was observed.