Background: Atrial fibrillation is an irregular, often very rapid heartbeat that can lead to clots and increase the risk of stroke, heart failure and other heart-related complications. Nurses' knowledge of patient management is critical in the cardiac care wards. Therefore, the study aimed to assess nurses knowledge towards atrial fibrillation and determine the differences in knowledge with regards socio-demographic variables. Methods: A descriptive cross-sectional study was conducted with an purposive sample of 200 nurses was selected through the use a non-probability sampling approach. This sample was distributed throughout three cardiac care unit according to the Babel Health Directorate, including (Margan Teaching hospital, Shahid AL-Mihrab center and Imam AL-Sadiq Hospital). The reliability of the questionnaire was achieved through a pilot study and then presented to experts to prove its validity. The total number of items included in the questionnaire was 40-items. The data was collected by using the self-report method and analyzed by the application of descriptive and inferential statistical data analysis approach. Results: The results of the study indicated that (55%) of the nurses exhibited a poor level of knowledge about atrial fibrillation.