An upper gastrointestinal endoscopic examination was performed, following a test for faecal occult blood, on a group of 108 patients with rheumatic complaints. The majority of the group studied had rheumatoid arthritis (RA) and 50% of the total group were anaemic. Every patient was taking a single nonsteroidal anti-inflammatory drug (NSAID). When the finding of blood in the faeces was compared with findings in the upper gastrointestinal tract, approximately half the subjects with ulcerative and inflammatory lesions had a positive test for blood. However, 50% of the subjects with an apparently normal upper gastrointestinal tract had a positive test for blood in the stool and these comprised the largest group of those examined. It was concluded that the finding of a positive faecal occult blood in such subjects is a poor indicator of ulcerative or inflammatory lesions of the upper gastrointestinal tract. The possible reasons for a finding of blood in the stool of patients taking NSAID who apparently have a normal upper gastrointestinal tract is discussed.