Report on 3 cases of spontaneous perforation of a pancreatic pseudocyst into the stomach; presenting symptom was in each case an acute upper GI-bleeding. The pseudocyst was endoscopically seen as a well delineated, hemorrhagic protrusion into the stomach. After full perforation the spontaneous ostium had the appearance of a surgical anastomosis. High amylase concentration in the aspirate ave further diagnostic evidence. All 3 patients survived, 2 of them without surgery.