Atrial fibrillation is very common in most old patients who need an adapted therapy due to their comorbidities. Before initiating an antiarrhythmic therapy, possible adverse effects, especially iatrogenic proarrhythmia, and extracardiac side-effects, must be considered. In geriatric patients with atrial fibrillation, heart rate control is the most frequent therapy. Oral anticoagulation plays a vital role in the therapy, but anticoagulation in old patients, who had a bleeding or stroke event, is challenging. Available data favor the use of anticoagulation in old patients with atrial fibrillation and suggest the use of direct oral coagulants, in most cases, over the use of vitamin K antagonists. However, a gap exists in the knowledge regarding the optimal dose in very old patients, particularly in patients with mild-to-moderate renal failure, with very low or high body mass index, and in those receiving medications with a high risk of metabolic interactions.