A prospective study of fifty-two patients undergoing fibreoptic upper gastrointestinal endoscopy was carried out in order to determine whether bacteraemia was a significant risk. Aerobic and anaerobic blood cultures were performed before, during and after endoscopy. Cultures were also taken from lesions (if any found) in the oesophagus, stomach or duodenum. No significant bacteraemia was identified, and bacterial growth was found in only one upper gastrointestinal lesion.