Objectives: To assess the impact of atrial fibrillation on stroke severity and short-term (1 month) mortality. Materials and Methods: Totally 200 patients admitted to Ain Shams University Specialized Hospital were recruited and diagnosed clinically to have acute ischemic stroke within 3 days. Patients with hemorrhagic infarctions were excluded. History taking about previous heart disease was taken, full general and neurological examinations were done. Full metabolic profile, full cardiac investigations, carotid duplex, MRI brain stroke protocol with initial clinical evaluation and after 1 month re-evaluation using (NIHSS ) scale. Results: All patients underwent transthoracic echocardiography which revealed absence of “A” wave corresponding to atrial fibrillation in 33 patients (16.5%). Those Patients with atrial fibrillation had a median NIHSS score of 11.00 with IQR of 6.00 - 18.50 at admission and 6.00 with IQR of 2.00 - 14.50 after one month. Patients with atrial fibrillation showed significantly higher NIHSS at admission than patients in sinus rhythm, P < 0.05. Magnetic resonance imaging findings showed that MRA showed significant intracranial vessel stenosis in 117 (79.1%) patients. 51 (34.4%) patients had lacunar infarction, 65 (43.9%) patients had partial anterior circulation infarction, 25 (16.2%) patients had posterior circulation infarction and 7 (4.7%) patients had total anterior circulation infarction. 111 (75%) patients showed leucoaraiosis. Conclusion: Atrial fibrillation was found not to have significantly statistical effect on stroke severity and short term mortality.