300 mg/day phenylbutazone, 210 mg/day indomethacin, and 600 mg/day pyrasanone were administered for 14 days to three randomised groups of patients respectively, consisting of a total of 76 subjects with various forms of non-infectious inflammation (osteoarthritis, fibrositis, rheumatoid arthritis, gout, phlebitis), in a double-blind trila designed to determine the activity of the three drugs and their tolerance. In 36 cases, gastroscopy was performed before and after the treatment. On the basis of doses that were equivalent as far as their anti-inflammatory effect was concerned, epigastric pain and pyrosis were noted in about 31% of the series, though no significant difference could be made out between the three drugs. Gastroscopic evidence of erythema (8 cases), multiple erosion (2 cases), pomphoid gastritis (1 case), and duodenal ulcer (1 case) was obtained in subjects treated with phenylbutazone or indomethacin, and of erythema only (1 case) after pyrasanone. No relation could be established between the clinical symptoms and the gastroscopic findings.