124 patients with cerebrovascular ischemic disease were studied, 67 of them with irreversible neurological deficits, and the EEG-findings of patients with (50) or without cardiac arrhythmia (74) were compared. Moreover, the EEG-diagnoses of these patients were compared with 40 controls without cerebrovascular ischemic disease. Patients with irreversible neurological deficit had significantly more often cardiac dysrhythmia (51%) than patients with reversible neurological symptoms (28%). In patients with reversible neurological symptoms and in the control group no difference between patients with or without disturbance of the heart rhythm could be found. But in patients with irreversible neurological deficit in presence of cardiac dysrhythmia significantly more pathological EEG-findings could be found with significantly more pronounced EEG changes especially in presence of atrial fibrillation.