Acquired von Willebrand syndrome is a rare bleeding disorder with clinical and laboratory features closely resembling to hereditary von Willebrand disease. The syndrome may accompany various conditions, including malignant disorders, most often with Wilms tumor and adrenal cell carcinoma. In this report, the authors present a patient with AvWS in association with Ewing sarcoma for the first time in the literature. The abnormal bleeding tendency was successfully treated with fresh frozen plasma and did not recur after the first two courses of chemotherapy with clinical improvement.