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.