Von Willebrand's disease is common hemorrhagic disorder that deserves particular attention in the patient undergoing open-heart surgery, because of perioperative unexpected bleeding. The present case is atrial septal defect associated with Willebrand's disease, affecting a 19-year-old female who has the past history of bleeding tendency with frequent subcutaneous bleeding. It is mandatory to maintain adequate levels of both factor VIII coagulation and ristocetin cofactor activities during the perioperative period. An infusion study of heat-treated evaluate the response and half-life of both factor VIII coagulation and ristocetin cofactor activities; and to calculate the effective dose and duration of the drug action as well as to formulate a protocol for patient's management in the perioperative periods in order for the surgical intervention to be performed uneventfully. Our case demonstrated that it is possible to perform an open heart surgery in patients with von Willebrand's disease without major bleeding as far as the levels of both factor VIII coagulation and ristocetin cofactor activities are maintained above 50% in the postoperative critical period.