Stress ulcer means an acute mucosal lesion of the upper gastrointestinal tract in sick patients, who have not had gastroduodenal ulcer before. Most often stress ulcers follow big operations, burns and different types of shock. Complications as respiratory insufficiency, paralytic ileus or infections favor the ulcer formation. The average age is 53 years, males are more often affected. The main localisation is the proximal stomach, less frequently the lesions are located in the duodenum and terminal oesophagus. The macroscopic type is an erosion or a superficial ulceration, a solitary ulcer is typically situated in the duodenum. From the view of pathogenesis three factors are mainly involved: hydrochlorid acid, a disturbance of microcirculation due to shock and a duodenogastric reflux of bile acids and lysolecithin. Most frequent symptom is upper gastrointestinal bleeding, but more than 50% are symptomless. Medical treatment is successful in 60-70%. The surgical treatment of choise is vagotomy in combination with circular sature or resection. Prevention of shock or respiratory insufficiency, permanent gastric suction, early food administration and intragastral application of antacids and cholestyramin are the essentials of stress ulcer prophylaxis.Key words: Stress ulcer -Acute gastric mucosal lesion (AGML) -Gastric mucosal barrier-shock.Lange Zeit wurde vermutet, dab Stressulcerationen mit einer Hypersekretion ein-