Pseudo-occlusion of the internal carotid artery represents a difficult diagnostic problem. Meticulous investigation is mandatory whenever there is any suspicion of pseudo-occlusion, since it can easily be removed with endoarterectomy. Fifteen patients were selected in the last twelve years from those participating in a prospective study on the natural history of total occlusion of the internal carotid artery. The mean follow-up was 4.2 years (ranging from 1 to 12). Pseudo-occlusion was diagnosed by duplex examination in the presence of a continuous signal with filling in of the spectral waveform window and no pulsatile flow. Arteriography showed a segmental occlusion of the internal carotid artery with reconstitution of flow in the distal portion of the vessel. Operations were performed under general anesthesia with EEG monitoring. Intraluminal shunt was necessary in only one patient. Patch closure of the arteriotomy was performed in two patients. All patients were put on Ticlopidin "sine die" after the operation. No mortality or strokes occurred in the perioperative period. Two patients presented with ipsilateral TIA after 7 months and one year, respectively. We conclude that: the incidence of this disease is low; the performance of duplex scan in combination with arteriography is essential in order to obtain the diagnosis of pseudo-occlusion; a strong suspicion of carotid pseudo-occlusion should always spring to mind when an apparently occluded carotid artery continues to be symptomatic or when, in asymptomatic patients, there is some discordance between angiography and Doppler or duplex scan findings; pseudo-occlusion should be considered an indication for urgent operation only in selected symptomatic patients.