OBJECTIVES: Atrial Fibrillation (AF) is the most common chronic arrhythmia occurring worldwide in the presence of other cardiovascular disease. The objective of the current study is to determine real-life treatment patterns for patients with AF in Latin America.  METHODS: We conducted 59 face-to-face interviews with cardiologists in four Latin American countries--Argentina, Brazil, Chile and Venezuela-- to assess medical treatment. Information from 240 patients from private and public institutions was evaluated using CHADS2 scores to identify patients’ risk and to determine treatment.  RESULTS: Patients with AF undergo a 3-step process to define their treatment course: (1) AF evaluation and diagnosis. (2) AF classification: paroxysmal, persistent, and permanent. (3) Clinical treatment focused on stroke prevention based on symptom relief, optimal treatment of concomitant cardiovascular disease, rate control and correction of rhythm disturbance. Overall in all four countries, analysis shows that the majority of patients with AF were diagnosed right before or at the time of first stroke.  The most common type of AF was permanent, except in Chile which was paroxysmal. The preferred antiarrythmic was amiodarone; the primary vitamin K antagonist used was warfarin in Brazil and Venezuela and acenocumarol in Argentina and Chile. CONCLUSIONS: Results from the study suggest that there are no significant differences among countries and that the majority treat patients following international clinical guidelines. Although the individual health care systems need to be considered in terms of relationship of treatment patterns with resource use, it is reassuring to note that international standards of care are being embraced in major emerging markets.