Oral anticoagulant therapy (OAT) has increased substantially due to the aging population and prevalence rise of atrial fibrillation (AF). Medication adherence is important to achieve effectiveness and safety of OAT. The study aim was to investigate the relationship between health literary (HL) and the adherence to OAT in patients with atrial fibrillation (AF). This is a cross-sectional study conducted in a public cardiology clinic in Brazil, 2019. Sociodemographic and clinical data were collected by the review of medical records and interviews with patients. The relation between health literacy (HL) and adherence to OAT was investigated by a multiple logistic regression model.