Atrial fibrillation is becoming an increasingly important problem in cardio-oncology. Specific risk factors for atrial fibrillation occurrence include type of cancer disease and anticancer drugs. Anticoagulation is often abandoned. The CHA₂DS₂-VASc and CHA₂DS₂ scores may be important not only in predicting stroke but also in mortality. The role of new direct oral anticoagulants is growing, but they need to be used in a personalized approach depending on the risk of unbeneficial interactions with cancer treatment and the risk of bleeding.