Bleeding is the most frequent complication of peptic ulcer disease. Patients with a previous ulcer hemorrhage have a high risk for future bleeding episodes. Therefore, treatment aiming at ulcer prophylaxis is mandatory. Helicobacter pylori infection, acid/pepsin and intake of Aspirin or NSAIDs are the main causal factors involved in the pathogenesis of peptic ulcer disease. Ulcers induced by nonsteroidal anti-inflammatory drugs can be cured by gastric acid suppression (e.g. omeprazole) and prevented by withdrawal of the ulcerogenic substances or co-medication with omeprazole or misoprostol. Acid and Helicobacter pylori are necessary, albeit by themselves not sufficient factors in the causal web of the formerly idiopathic, gastritis-associated peptic ulcer disease of the stomach and the duodenum. Maintenance therapy with antisecretory drugs results in a marked decrease of ulcer recurrences and probably further ulcer complications after an index bleeding, but a definite cure of the ulcer disease is not feasible in the majority of patients. The proportion of patients remaining in remission is dependent on the degree of gastric acid suppression. Therefore, potent antisecretory drugs such as the proton pump inhibitor omeprazole should be used if a physician decides to initiate a long-term maintenance therapy. Several studies have demonstrated beyond doubt that cure of Helicobacter pylori eradication resulted in a stable remission of gastric and duodenal ulcer disease. In addition, a true reinfection after apparent eradication of the bacteria has been rarely observed in adults.(ABSTRACT TRUNCATED AT 250 WORDS)