BACKGROUND: Atrial fibrillation (AF) is an important preventable cause of stroke. Anticoagulation (AC) therapy can reduce this risk. However, prescribing patterns and outcomes in patients with non-valvular AF (NVAF) from Latin American countries are poorly described. METHODS: Using data from the Global Anticoagulant Registry in the FIELD-AF (GARFIELD-AF), we examined the stroke prevention strategies and the 1-year outcomes in patients from four Latin American countries: Argentina, Brazil, Chile, and Mexico. RESULTS: A total of 4162 patients (2010-2014) were included in this analysis. At the time of AF diagnosis, 39.9% of patients were prescribed vitamin K antagonists (VKA) ± antiplatelet (AP) therapy, 21.8% non-VKA oral anticoagulant (NOAC) ± AP, 24.1% AP only and 14.1% no antithrombotic treatment. The proportion of moderate-high risk patients receiving no AC therapy at participating centers was highest in Mexico (46.4%) and lowest in Chile (14.3%). During 1-year follow-up, the rates of all-cause mortality, stroke/SE and major bleeding were: 5.77 (95% CI) (5.06-6.56), 1.58 (1.23-2.02), and 0.99 (0.72-1.36) and per 100 person-years, respectively, which are higher than the global rates across all countries in GARFIELD-AF. Unadjusted rates of all-cause mortality were highest in Argentina, 6.95 (5.43-8.90), and lowest in Chile, 4.01 (2.92-5.52). CONCLUSIONS: GARFIELD-AF results describes the marked variation in the baseline characteristics and patterns of antithrombotic treatments in patients with NVAF in four Latin American countries. Over one-third of patients with a moderate-to-high risk of stroke received no AC therapy, highlighting the need for improved management of patients according to national guideline. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362.