Some time after deletion of occlusion of the appropriate artery, 20 patients had transient ischemic attacks and seven had strokes. The common statement that transient ischemic attacks cease when an artery becomes occluded must, therefore, be modified. Seventeen of the 20 patients reported here developed symptoms weeks to years after the appropriate artery was known to be occluded, while 10 attacks occurred within 1 week after occlusion. Embolism through collateral circulation probably accounts for the delayed ischemic events in most of the patients, and hemodynamic factors in a few. The stump of the occluded artery may be the site of atheromatous ulceration. The possibility of revascularization procedures for patients with occluded arteries makes pertinent these observations about potential embolic sources.