Angiodysplasia of the colon is increasingly recognized as a cause of obscure gastrointestinal haemorrhage. On review of 71 patients with angiodysplasia, 40 came to surgery. Of these, nine (22.5 per cent) were also found to have small bowel lesions, either at the original laparotomy (7) or later when further investigations were performed for recurrent bleeding. Angiodysplasia can only be confidently diagnosed as the source of blood loss if seen to be actively bleeding. If a synchronous small bowel lesion is seen, we recommend that it should be removed at the same time as the colectomy.