Angiodysplasia is uncommon and frequently undiagnosed and presents a taxing surgical problem. It is usually diagnosed for unexplained gastrointestinal bleeding. Angiography gives a little information about wax and wane pattern of bleeding in the lesion. We experienced I case of angiodysplasia in G-I tract(especially colon) diagnosed in the Seoul National University Hospital. This report summarized our experience and review of east and west literature