Atrial fibrillation (AF) is the most common heart rhythm disorder in the world. It is estimated that by 2050, the number of people with AF will exceed 60 million. Important risk factors for AF include lifestyle, including eating habits. Given that coffee is the third most commonly consumed beverage in the world (after water and tea), the question arises as to how it may affect the risk of AF. Numerous chemical compounds contained in coffee have an electrophysiological effect. Habitual drinking of moderate amounts of coffee allows for the development of antiarrhythmic mechanisms. In the case of occasional coffee drinking, proarrhythmic mechanisms predominate. Therefore, if a person decides to drink coffee as part of healthy eating habits, they should do so regularly and in moderate amounts (2–3 cups/day). In patients with existing AF, in the absence of contraindications, regular drinking of two to three cups of coffee reduces the risk of death and serious cardiovascular events. This chapter summarizes current knowledge about the effect of coffee drinking on AF.