Nine cases of angiodysplasia have been angiographically identified in the past eight years at the two teaching and two major private hospitals in the West Los Angeles-Santa Monica area. In seven patients, repeated massive hematochezia whose source had escaped previous intensive diagnostic studies, was the indication for angiography. Two malformations were found incidentally during an angiogram for an unrelated problem. Four of the patients had had a previous angiogram which failed to show the lesion. Eight of the nine patients had right colon vascular malformations, but one had jejunal angiodysplasia as well. One patient had a midileal vascular malformation which appeared in the right lower quadrant on the study. Six of the seven underwent resection of the implicated bowel, and none have rebled. The series suggests that angiodysplasia may not be as rare as commonly assumed and in four cases escaped detection even angiographically at least initially. The lesions may be multiple and their anatomical site radiologically deceptive. Finally, these vascular malformations may be an incidental finding, and though demonstrable angiographically, may not necessarily be responsible for bleeding in the patient older than fifty years.