One potential complication of carotid disease is progression to total occlusion while under medical management. To investigate this important issue, 44 patients (31 men; 13 women) ranging in age from 44 to 83 (mean, 65.9) years with internal carotid artery occlusions as a result of arteriosclerosis were identified among 993 patients undergoing carotid angiography from Jan. 1, 1985 to Dec. 31, 1989, and their prior medical records were reviewed. Clinical presentations included stroke in 9 (20.5%), retinal infarct in 8 (18.2%), transient ischemic attacks in 10 (22.7%), amaurosis fugax in 4 (9.1%), nonhemispheric symptoms in 3 (6.8%), and 10 (22.7%) were asymptomatic. A review of these patients' medical records documented that prior hemispheric symptoms referrable to the now occluded internal carotid artery had occurred in five (55%) of the nine patients who were admitted with stroke, five (62%) of the eight patients with a retinal infarct, six (60%) of the 10 patients who were admitted with a transient ischemic attack, all four (100%) patients who were admitted with amaurosis fugax, one (33%) of three patients with nonhemispheric symptoms, and in seven (70%) of the 10 patients who were asymptomatic when the internal carotid artery occlusion was identified angiographically. In summary, 28 (64%) of the 44 patients had experienced ipsilateral symptoms from 2 to 120 (mean, 30) months before the diagnosis of internal carotid artery occlusion; only eight (28%) had undergone noninvasive or angiographic evaluation, and all were placed on antiplatelet therapy when prior hemispheric symptoms developed.(ABSTRACT TRUNCATED AT 250 WORDS)