Congenital arteriovenous malformations of bowel occurring as solitary or multiple lesions may cause obscure gastrointestinal bleeding with negative radiological and endoscopic studies. These malformations may be missed at laparotomy and selective visceral angiography is essential for localisation and to assess is extent of the lesions. An immediate post-resection radiograph with barium injection into the arteries is recommended to assess the completeness of the resection before abdominal closure. There is a need, when discussing vascular malformations of the bowel, to distinguish the acquired degenerative colonic lesions from the congenital arteriovenous malformations which are more common in the small bowel.