The treatment of patients with chronic gastrointestinal bleeding can be a frustrating diagnostic challenge. In the past 10-15 years, a variety of new diagnostic procedures (e.g., fiber-optic endoscopy, scintigraphy, and double-contrast barium studies) have become available to examine these patients. Despite these new procedures, a small number of patients continue to bleed without a defined cause. We sought to evaluate the role of visceral angiography in patients with chronic gastrointestinal bleeding in whom findings on an extensive noninvasive workup have been normal. Between 1983 and 1990, we obtained angiograms on 36 such patients. The cause of bleeding was established by angiography in 16 patients (44%). In 11 of these 16, angiography revealed only a structural abnormality without active bleeding. Twenty patients had normal angiographic findings. No angiograms were false-positive, but three were false-negative (8%). No complication occurred as a result of the angiographic procedures. Our experience shows that visceral angiography can provide a positive diagnosis in a significant number of patients with chronic gastrointestinal bleeding of obscure origin in whom all other diagnostic measures have been unrevealing. Despite improvements in noninvasive diagnostic techniques, angiography still remains an important tool for examining this group of patients.