A case-series was performed in the Emergency Service of the University Hospital V. I. Lenin. The universe of the study was 413 patients in Observation at the Emergency Service of Internal Medicine. Considered as an objective was to determine the behavior of the different clinical, epidemiological and therapeutic variables of the patients with atrial fibrillation and with risk to develop cerebrovascular disease. Of these patients, 165 were selected according to the inclusion criteria. The main results were that the most frequent clinical pattern of presentation was recent diagnosis followed by recurrent and permanent diagnosis and that after 60 years of age the highest risk to develop stroke was in patients with permanent clinical pattern which were not properly protected to prevent it. We concluded that if cerebrovascular disease is to be prevented, then it is necessary to give the patients the proper anticoagulants and antiplatelet medications. We recommend insisting in the application of the protocols of management.