Background and purpose: Adequate diagnosis of arrhythmias, including paroxysmal atrial fibrillation (PAF), is an important part of stroke workup. 24 hour- Holter ECG may improve the detection of arrhythmias and PAF. Therefore, the authors evaluated systematic 24-hour Holter ECG monitoring to detect arrhythmias and for the workup of patients with acute stroke. Methods: 162 patients of acute stroke or transient ischemic attack (TIA) without known AF and 50 normal people were enrolled in a cross-sectional study of 24 hour - Holter ECG monitoring. All patients underwent 24 hour - Holter ECG monitoring directly after admission. Results: A total of 162 patients were enrolled (mean age, 63,6 years [SD, 12,7 years], 26,5 percent women). The proportion of cardiac arrhythmias was 88,30 percent. PAF was detected in 28 out of 162 patients (17,30 percent). The presence of arrhythmias, supra ventrical arrhythmias, ventrical arrhythmias and severe ventrical arrhythmias was higher in patients withNIHSS score or = 7 than in patients with NIHSS score 7 (p0,05). The risk of cardiac arrhythmias in patients with consciousness disorders, NIHSS score or = 7 and with brain stem lesion area was 2,29, 3,56 and 5,08 times higher. Conclusions: It is confirmed that the proportion of cardiac arrhythmias in patients with stroke is high. Therefore, 24 hours - Holter ECG should be used for early detection cardiac arrhythmias especially in patients with consciousness disorders, high NIHSS score and with brain stem lesion area.