One hundred patients (50 male, 50 female) suffering from rheumatoid arthritis, treated for more than 6 months with steroid and/or non-steroid anti-inflammatory agents were studied using barium X-rays and gastro-fibroscopy. In 69, one or more gastric biopsies were taken during the endoscopy. The study showed a marked preponderance of ulcerous lesions in males, 9 of the 13 iatrogenic ulcers being found in this sex. It also confirmed the frequency of gastritis and the absence of any correlation between clinical signs and radio-endoscopic findings as well as between the latter and histopathological data. An ultra structural study carried out in 20 cases revealed focal lesions of the clear cells of the neck of the fundus and antral glands and, in 4 cases, marked changes in the gastric endocrine cells.