OBJECTIVES: To examine the cost impact of atrial fibrillation (AFib) in patients with atherothrombotic diseases in a German statutory health insurance population. METHODS: Study design: A retrospective review of the medical, hospital and pharmacy claims data (2004–2005) in the database of a German statutory health insurance. We reviewed pharmacy and medical claims data for the years 2004–2005 from an insurance covering about 5 Mio insurees. The data of patients suffering from cardiovascular diseases (myocardial infarction, stroke or PAD) were available. By using the documented ICD-10 codes (I48.10, I48.11, and I48.19) for hospitalizations we identified patients who experienced Afib during 2004 and 2005. For these patients we reviewed all the charges incurred for a one-year period after the initial index event on the basis of weekly costs and from the third party payer’s perspective. RESULTS: A total of 14,798 patients (mean age: 72±10 years) with Afib could be included in the analysis. The majority of the patients (55%) were female. The cost for atrial fibrillation patients for one year was €7690. The largest portion of the total cost (78%) resulted from the costs for hospitalization while the initial hospital stay was associated with 30% of total costs. Approximately 100% of the study population received prescription drugs at an average cost of €1155 per prescription drug user. Compared to the duration before the initial diagnosis of Afib, the costs increase by the factor 1.4 during the first year after the event. The majority of costs one year after the event arise during the first 10 weeks (approx. 50%). CONCLUSIONS: An acute Afib-event in patients with atherothrombotic diseases represents a significant financial burden from the perspective of the statutory health insurance population. Improved management of the condition is needed to reduce the cost of treatment associated with AF.