Abstract Massive bleeding from a pancreatic pseudocyst is a rare condition that poses a diagnostic and therapeutic challenge. A 36-yr-old woman presented with acute pancreatitis due to gallstones. Twenty-two days later, she developed severe abdominal pain and hypotension. CT scan revealed hemorrhage into a pancreatic pseudocyst and a large amount of free blood in the peritoneal cavity. At laparotomy, 8 L of blood was evacuated from the peritoneal cavity and 14 units of blood were transfused. The gastroduodenal artery was found to be the cause of the bleeding and was undersewn. A pancreatic necrosectomy was performed and the cavity was packed. The packs were removed the following day. Postoperatively, pancreatic collections were aspirated under ultrasound guidance on three occasions. She was discharged 50 days after admission and had an open cholecystectomy 1 month later. She remains well 1 yr after surgery.