The present study retrospectively evaluates all endoscopies performed on a medical intensive care unit during the period from 1986 to 1992. During these seven years, 415 endoscopies were performed of which 77.8% were done as an upper gastrointestinal endoscopy. The most frequent findings consisted in esophagitis (23.6%), ulcers of the stomach or duodenum (20.2%), esophageal varices (10.1%) and erosive-hemorrhagic gastritis (9.6%). More than 2/3 of all endoscopies were performed because of an gastrointestinal bleeding with upper bleeding being three times more frequent than lower bleeding. The endoscopy was able to identify the cause and site of bleeding with certainty or high probability in 92.8%. Esophagitis was the most frequent cause of bleeding (30.7%) followed by ulcers in the duodenum and stomach (25.6%), esophageal varices (14.8%) and erosive gastritis (13.7%). In more than 90% of patients with esophagitis a nasogastric tube had been administered during the two preceding days. Therefore, the tube is probably responsible for the esophagitis. The present data show that bleeding from esophageal lesions are about ten times more frequent in patients treated in an intensive care unit when compared to data published for the general group of patients with gastrointestinal bleeding. Considering the frequency of bleeding from esophagitis in intensive care patients, an administration of a nasogastric tube should be done only when mandatory.