Abstract: Warfarin is one of the common oral anticoagulants. Anticoagulant response is affected by the amount of dietary Vitamin K, various drugs, foods and herbal treatments. Although, hemorrhage is one of the side effects of warfarin, tongue hematoma is a rare complication. In this research, 50 years old male patient developed tongue hematoma during the prophylactic warfarin treatment due to the atrial fibrillation is presented.