Background: It is unknown whether physicians' attitudes about the management of atrial fibrillation (AF) reflect the recommendations of published guidelines. Methods: To obtain information about physicians' attitudes about management of AF, a questionnaire was returned by 904 (20.1%) of 4500 physicians involved in managing AF (385 cardiologists, 326 internists, and 193 electrophysiologists). The cardiologists and internists were from Massachusetts or California; the electrophysiologists were from around the United States. The questionnaire called for 86 separate answers about use of resources and drug therapy for different types of AF, including recent-onset AF, paroxysmal AF, and chronic AF of less than 6 months' and more than 3 years' duration. Results: Transthoracic echocardiography and thyroid function were requested by more than 90% of physicians; transesophageal echocardiography and catheterization were requested by 10% of physicians. To control ventricular response, digoxin was the overwhelming first-line therapy; calcium channel blockers were favored over beta-blockers for adjunct therapy. To prevent thromboemboli, warfarin sodium was preferred for chronic AF; warfarin or aspirin were equally considered for paroxysmal AF. In considering sinus rhythm, respondents agreed about factors determining whether to revert, the number of drug trials, and the first-line drug choice (quinidine sulfate) but disagreed about second-line antiarrhythmic drugs and whether to hospitalize the patient before initiating drug therapy. Conclusions: Physicians ranging from primary care providers to subspecialists agree on issues of AF management such as heart rate control and anticoagulation. Attitudes vary widely about issues such as antiarrhythmic drugs.