Aneurysmal degeneration of gastroduodenal and pancreaticoduodenal arteries due to acute and chronic forms of pancreatitis is uncommon. Gastrointestinal hemorrhage secondary to these vascular lesions has been recognized in only 23 patients. Eight of these patients, including five with gastroduodenal and three with pancreaticoduodenal artery aneurysms, have been encountered at the University of Michigan Medical Center. Selective mesenteric arteriography provided the greatest diagnostic specificity. Computerized axial tomography was of discriminate diagnostic value in two patients. Seven of eight patients underwent surgical therapy: transcystic arterial ligation and external pancreatic pseudocyst drainage (four), arterial ligation with abscess drainage (two), and pancreaticoduodenectomy (one). Three patients died after operation from intraabdominal sepsis as well as delayed arterial hemorrhage. Earlier operative intervention, dictated by the patient's clinical status and relevant anatomic findings, may improve survival rates in this complex disease state.