The erosion of a pancreatic pseudocyst into an adjacent artery is a rare and highly lethal complication of pancreatitis with reported death rates of 12% to 40%. The majority of patients had bleeding from the splenic artery, the gastroduodenal artery and the anterior pacreaticoduodenal artery. Exceptionally, some cases with bleeding from the superior mesenteric artery, or hepatic artery were reported. We report the case of a 50 year old patient having a cataclysmic upper gastrointestinal bleeding due to an erosion of the superior mesenteric artery by a pancreatic pseudocyst, and discuss contemporary methods in diagnosis and management of the condition.