Cardiac dysrhythmia may be responsible for signs of cerebrovascular insufficiency in some patients. Ten patients with cerebrovascular insufficiency were monitored for up to 24 hours with the Holter EKG monitor. Eight of the patients had transient ischemic attacks and two had mild deficits from a completed stroke. Eight of the ten patients had associated abnormal cerebral angiography, the most frequent finding being carotid stenosis. Holter EKG monitoring in these ten patients showed no abnormalities in four patients. The remaining six had a variety of cardiac dysrhythmias. Although there were a variety of cardiac, cerebrovascular, and neurological abnormalities in these ten patients, six of these patients had a disturbance in cardiac rhythm or conduction which could have been directly associated with or suggest an etiology for the patient's neurological event.