Despite of sound evidence, that oral anticoagulation reduces substantially the incidence of stroke-events in patients with atrial fibrillation and concomitant risk factors, in daily practice only a part of these patients is in fact treated with anticoagulation. The aim of this cross-sectional study was to evaluate to which extent existing guidelines for the treatment of patients with atrial fibrillation are transformed in the "real world" context of a Swiss urban network of primary care providers. The greatest part (88.4%) of the included patients with atrial fibrillation had a high risk for thromboembolism and herewith the indication for anticoagulation was given. For a primary care collective the amount of patients with anticoagulation was high: 74.1% did receive this kind of preventive therapy. 89% had robust International normalized ratio (INR) values within the recommended range (INR 2.5-3.5). The most common reasons not to prescribe oral anticoagulation were: old age (17.5%; mostly in combination with other reasons), risk of falls (16.5%), medical indication not given (16.5%). Thus the recommendations of the guidelines have been transformed into practice for a bigger part of the included patients. Given these results a broadly implemented quality-improvement-project to bring up the anticoagulation rate even higher hardly seems to be efficacious and is presently not of top priority in this network of primary care providers.