Today the upper gastrointestinal endoscopy is the diagnostic tool of choice to detect peptic gastroduodenal lesions. In case of substantial gastric outlet obstruction or strong suspicion of perforated ulcer, an upper gi-transit with barium or water soluble contrast medium in suspected perforated ulcers may be useful. Gastric ulcers are endoscopically controlled up to their complete healing and biopsies taken at each endoscopy in order to rule out gastric cancer. In contrast, duodenal ulcers are rarely malignant and uncomplicated duodenal ulcers, correctly treated with omeprazole over 8 weeks do not necessarily need a final endoscopic control. Since about 5% of duodenal ulcers treated with H2 blockers or mucosal protective agents do not heal within 8 weeks however, an endoscopic control of the healing is recommended. In peptic ulcer patients tests for detection of helicobacter pylori are only needed in presence of a hard indication for immediate eradication: Frequent ulcer recurrencies, complicated ulcer disease or very painful ulcer relapses, because the eradication therapy is often not well tolerated and the patient compliance therefore compromised. 30% of helicobacter infected patients have antibiotic resistant strains and there is no sufficient longterm experience with the eradication therapy available (4) to 8 weeks after treatment of the helicobacter pylori infection the effect on ulcer healing and infection should be verified. Determinations of plasma gastrin levels in peptic ulcer patients are mandatory in patients with suspected Zollinger-Ellison syndrome or patients with treatment resistant ulcers or recurrent ulcers after vagotomy or partial gastric resection.(ABSTRACT TRUNCATED AT 250 WORDS)