Clinical characteristics of 12 patients with carotid occlusive disease who experienced episodes of repetitive involuntary movement were analyzed and correlated with laboratory findings. The majority of patients had rhythmic involuntary movements of one or both extremities on one side, which were characteristically precipitated by standing, walking, or hyperextension of the neck and were promptly alleviated by assuming a sitting or supine position. Six patients had a history of a prior transient ischemic attack or stroke. Electroencephalograms contained no epileptiform activity at rest or during sleep in any patient or during the involuntary movements in 2 patients. Cerebral angiography revealed either occlusion or high-grade stenosis of the internal or common carotid artery on the side opposite the involuntary movement in all patients. We conclude that the repetitive involuntary movements result from transient hemodynamic ischemic episodes rather than partial (focal) epilepsy.