This international study is a prospective non-interventional observational cohort study of patients with non-valvular atrial fibrillation who are prescribed rivaroxaban under routine treatment conditions to prevent stroke or non-central nervous system systemic embolism. Patients will be followed up for 1 year or until 30 days after end of rivaroxaban therapy in case of therapy was discontinued earlier than 12 months. Serious adverse events will be followed up adequately. Laboratory values (e.g., Hb, HCT, haemoccult) should be documented for each point in time they were measured.