This study was undertaken to describe the declared management of atrial fibrillation in community medicine in France for patients between 50 and 80 years of age, and to estimate the total cost of treatment for Society in the year 2000. A questionnaire was sent to a sample of 306 private sector cardiologists, representative for their geographic location: 100 replies were received. Only 10% of cardiologists prescribed a treatment in patients without cardiovascular precedents who had a single regressive episode of atrial fibrillation and three quarters of them advised follow-up. This management cost an average between 228 and 296 Euros/year. When the episode of fibrillation was persistent at the time of consultation, 82% of practitioners prescribed antiarrhythmic reduction (amiodarone) after antithrombotic treatment (oral anticoagulants) followed by an antiarrhythmic therapy (class lc mainly) with an average cost of 659 to 783 Euros/year. In patients with previous cardiovascular disease, when a first episode of atrial fibrillation was present at the time of consultation, 92% of cardiologists prescribed pharmacological reduction with amiodarone, followed by long-term therapy when successful for an average cost of 755 to 1,092 Euros/year. All cardiologists requested systematic blood tests to search for thyroid complications of amiodarone with an average cost of 59 Euros/year. The costs were high, especially in chronic and recurrent pathology: the cost of treatment of the first two episodes of atrial fibrillation in the over 65 age group was 305 million Euros/year.