Normal angiograms and carotid pathology. Nonstenotic ulcerated atherosclerotic plaques of the carotid arteries may be associated with symptoms of transient ischemic attacks, amaurosis fugax, and stroke. Preoperative evaluation of patients with these symptoms has traditionally included ultrasound and arch aortography angiograms of the area of the carotid bifurcation. Recent evidence has shown that ultrasound is more accurate in detection and morphologic delineation of these nonstenotic lesions. We analyzed the hospital records of 21 patients with ultrasonographic evidence of disease in whom arteriograms were negative. The patient group comprised 15 men and six women, with an average of 66 years. All patients had symptoms of hemispheric transient ischemic attacks and were evaluated with B-mode ultrasound and arteriography. Ultrasound was positive and arteriogram "negative" in all of the patients (i.e., described by the radiologist as without hemodynamic significant disease or ulceration, or as normal). The ultrasound diagnosis was confirmed at operation with findings of 20 to 50 per cent stenosis and ulcerative plaques. At retrospective review of the arteriograms, three ulcerations were found in the 21 patients. We conclude that B-mode ultrasound better defines nonstenotic ulcerative lesions and decisions to perform carotid endarterectomy may be based on either positive test. An ulcerative plaque by B-mode ultrasound and appropriate symptoms, therefore, may not require angiography before operation. 