A 4-year-old Japanese girl had a congenital disorder that was characterized by recurrent thrombocytopenia, hemolytic anemia, hematuria, and proteinuria, which were repeatedly improved by the infusion of factor VIII concentrate. She developed the similar symptoms within 1 h after 1-desamino-8-D-arginine vasopressin (DDAVP) administration. Coagulation studies 30 and 60 min after DDAVP infusion showed a disappearance of large factor VIII:von Willebrand factor (VIII:vWF) multimers, which was the same abnormality that was observed at acute episodes. There were no significant changes in the plasma levels of 6-keto-prostaglandin F1 alpha and thromboxane B2 before and after DDAVP infusion. These results provide further support that VIII:vWF is directly involved in the pathogenesis of this congenital disorder.