Aims: To gain insight in the prognosis and treatment of atrial fibrillation (AF) patients during 1-year follow-up in the Euro Heart Survey (EHS) on AF. Methods and results: The EHS enrolled 5333 AF patients in 2003-2004. One-year follow-up data were available for 80%. Of first detected AF patients, 46% did not have a recurrence during 1 year, paroxysmal AF largely remained paroxysmal AF (80%), and 30% of persistent AF progressed to permanent AF. Many treatment changes occurred since baseline. Oral anticoagulation was started in 19% and discontinued in 16% of all patients. Of patients initially on rhythm control 27% did not receive rhythm control during follow-up, whereas 15% of patients initially on rate control received rhythm control. Mortality was highest in permanent AF (8.2%), but also substantial in first detected AF (5.7%). In multivariable analysis, sinus rhythm at baseline was associated with lower mortality, but no significant effect was observed regarding the application of either rhythm or rate control. Conclusion: The EHS on AF provides unique prospective observational data on AF progression, long-term treatment, prognosis, and determinants of adverse outcome of the total clinical spectrum of AF in a European cardiology-based patient cohort.