Real-time B-mode ultrasonography and ocular pneumoplethysmography (OPG-G) were used to evaluate 41 patients (54 arteries) following carotid endarterectomy. Thirteen patients had bilateral procedures. Recurrent stenosis was observed in three (6%), and postoperative occlusion in three (6%). In one symptomatic patient, the origin of an occluded external carotid artery was the source of atheroemboli. Only two of the seven patients were symptomatic and three of the seven had hemodynamically insignificant stenoses. Of the three patients with recurrent stenosis, two had a normal OPG-G and demonstrated the value of combinate noninvasive evaluation. The noninvasive diagnosis in these two cases was based on B-mode ultrasonography. Of the three postoperative occlusions, one had a normal OPG-G. Since the OPG-G cannot distinguish stenosis from occlusion, B-mode ultrasonography was necessary to demonstrate the presence of an occluded internal carotid artery and the absence of internal carotid flow in each case. B-mode ultrasonography also permitted the identification of several characteristic postoperative findings. An intimal shelf was often observed, corresponding to the proximal limit of the endarterectomy. Seventy-four per cent demonstrated thickening of the arterial wall and 45 per cent were observed to have calcification in the area of the endarterectomy. The true incidence of recurrent disease following carotid endarterectomy is uncertain, but it probably exceeds those estimates based on symptomatic recurrence. Because of the incidence of asymptomatic and/or hemodynamically insignificant disease, we recommend the routine use of noninvasive studies following carotid endarterectomy.