OBJECTIVES: Evaluate the costs of patients with known diagnosis of atrial fibrillation who received medical care related to stroke episodes, under the Private Healthcare system perspective. METHODS: A retrospective evaluation of a database with 3 million individuals was conducted to identify patients diagnosed with Atrial Fibrillation (AF) using the International Classification of Diseases version 10 (ICD10) I48 code (Flutter and atrial fibrillation) between 2009 and 2010. From the identified cohort, patients presenting the following codes: ICD10 I64, I63, I66 and I69, were further analyzed from 2009 to 2012. Costs associated to the episodes such as medications, exams, procedures, hospitalizations and others were evaluated. RESULTS: From 1,898 patients presenting the AF diagnose identified in the database, 66 Presented a diagnosis of stroke. The 66 patients cost BRL 2,325,250.61 to the supplemental health service, being BRL 2,193,185.50 spent with 21 patients hospitalizations due to stroke. CONCLUSIONS: If not controlled, AF may impose a significant morbidity due to increased susceptibility for thromboembolic events such as stroke and its complications, causing important spending beyond hospitalizations and other significant direct and indirect costs to the private health care system.