Purpose: Catastrophic antiphospholipid syndrome (CAPS) is a variant of antiphospholipid syndrome and presents with life-threatening symptoms of multiorgan failure due to thrombosis. We present a patient with CAPS secondary to an ovarian cancer In such cases, it is believed that the thrombotic risk disappears after surgical removal of the cancer The intraoperative management was challenging because of the risks of two opposing complications: catastrophic exacerbation of the thrombotic tendency triggered by the surgical stimulus and major bleeding due to the necessary anticoagulation. We describe the intraoperative management of hemostasis in a patient with CAPS. Clinical features: A 44-yr-old female patient with CAPS underwent resection of an ovarian cancer, which was suspected to be associated with her coagulation abnormality. She had both arterial and venous thromboembolism, including cerebral infarction, embolic gangrene, and pulmonary emboli. Serological examinations revealed increased anticardiolipin IgG antibody and decreased protein C activity. Before surgery, an inferior vena cava filter was placed to prevent perioperative pulmonary embolism, Prostaglandin E-1 (PGE(1); 100 ng(.)kg(-1.)min(-1)) was given intraoperatively to suppress platelet aggregation and thrombin generation and to maintain arterial blood flow. No apparent coagulation abnormalities were observed during surgery, neither hypercoagulation nor a tendency to bleed. No additional thrombotic symptoms developed during a six-month follow-up. Conclusion: The use of PGE(1), an inhibitor of thrombin formation and platelet function, and placement of an inferior vena cava filter were associated with the uneventful surgical resection of an ovarian cancer in a patient with CAPS.