Amongst 1035 patients who underwent oesophago-gastro-duodenal fibroscopy as an emergency for an upper gastrointestinal haemorrhage between January 1973 and May 1977, 100 required surgery. The operative findings were compared with those of endoscopy. In 92 cases, surgical exploration found the same lesions that the endoscopist had reported as being responsible for the haemorrhage. In 14 of these patients, surgical exploration provided complementary data to the endoscopic findings. In the other 8 patients, there was disagreement between the surgical and endoscopic findings. In particular, there were 5 diagnostic errors: 2 false negatives, 1 error of localisation of the lesion and 2 errors of interpretation. The earlier endoscopy is performed, the better are the results: discovery of the bleeding lesion and elimination of other non-haemorrhagic lesions.