The authors use the term "complicated migraine" to describe the onset of neurological disorder occurring during an acute attack in a patient with chronic migraine. The disturbance may last for long periods or may be permanent, and these irreversible cerebral lesions have to be differentiated from the transient neurological effects characteristic of ophthalmic on secondary migraine. Patients with migraine and retinal lesions, as well as those with ophthalmoplegic or familial hemiplegic migraine, were excluded from the study. The seven cases reported included 5 women and 2 men with an average age of 30 years (from 14 to 51 years). A more or less severe lesion in a hemisphere was present, which led to sensory-motor signs of a hemiplegia (4 cases), an aphasia (4 cases), and a homonymous lateral hemianopia (3 cases). Exploration revealed the presence of an ischemic cerebral lesion in all cases. One or more arterial occlusions were also noted in 5 out of the 6 patients who were investigated by angiography. All cases showed the presence of the criteria thought to be essential for associating the cerebral ischemic lesion with migraine. 1) the patient had true migraine, 2) there was a close chronological relationship between the migraine attack and the lasting neurological disorder, 3) no other associated vascular disease was present (atheroma, cardiopathy). The very severe and prolonged spasm, which could be the cause of neurological disturbances in secondary and ophthalmic migraine, does not appear to be sufficient for producing an irreversible ischemic lesion and, more especially, a persistent vascular obstruction. The roles played by edema of the arterial wall and parietal changes in the vessels are discussed. It could be that thrombosis formation is encouraged by the changes in blood coagulability which may be associated with a migraine attack. The fact that anomalies in platelet aggregation have been demonstrated merits closer study.