Gastroduodenal bleeding or perforation following renal transplantation constitute a serious complication with a high lethality. 82 patients with terminal renal insufficiency were grouped in 4 categories with increasing gastroduodenal risk factors. Parameters for judging gastroduodenal risk consisted of gastric acid secretion, history and endoscopic demonstration of acute or chronic ulcer disease. 33 transplant candidates of groups I (hypochlorhydria, no ulcer) and II (normochlorhydria, no ulcer) were treated by medical prophylaxis alone. 23/33 were transplanted without prophylactic surgery, 1 patient in group II with erosive duodenitis before transplantation died from bleeding duodenal ulcer. Patients of group III (hyperchlorhydria up to 40 mval/h, MAO, no ulcer) received selective proximal vagomty, patients of group IV (hyperchlorhydria, 40 mval/h MAO and/or ulcer) underwent selective gastric vagotomy and 50% gastric resection. In 25 of 49 patients of group III and IV prophylactic operations were performed without serious complications. In 16 later on transplantated patients no gastrointestinal bleeding occurred. 2 patients of group III without gastric operation had minor bleedings out of erosive lesions in the gastric antrum and duodenal bulb, that could be managed by medical treatment. The positive experience with prophylactic gastric surgery in this limited number of patients seems to advocate a broader application of such a protocol. A considerable rise in gastric secretion was demonstrated in 19/21 patients during the first 3 years following the commencement of dialysis, BAO rose by an average of 72,2%, MAO by 41%. Thus, gastric analysis should be repeated once a year. Erosive gastritis and duodenitis seem to predispose for bleeding episodes after renal transplantation, this diagnosis should prompt prophylactic SPV.