A 23-year-old woman presented with intractable iron-deficiency anaemia. A barium meal showed widespread mucosal abnormalities in the stomach and massive mucosal hypertrophy was found at laparotomy. Repeated tests for occult blood were negative but gastrointestinal haemorrhage was confirmed by isotopic blood labelling. In the face of persistent anaemia and radiological progression, total gastrectomy was performed, since when a normal blood picture has been maintained. The excised stomach showed hyperplasia of all the mucosal elements, minimal inflammation, and no obvious bleeding point. Blood loss was attributed to diapedesis from a greatly increased capillary network.