This article presents a case of an 88-year-old man who shows blue-violaceous discoloration on his fingers and toes, with a greater intensity on the third finger of right hand and the first, second and third toe of his right foot. The patient had been recently diagnosed with atrial fibrillation and met the criteria for oral anticoagulation with acenocoumarol, which had started two weeks earlier. When the treatment was discontinued, the bluish color of his fingers disappeared, for which reason the patient was concluded to present a rare adverse effect to treatment with dicumarin, making it necessary to replace it for another anticoagulant with a different mechanism of action.