A patient with a relatively localized occult carcinoma of the lung and hemorrhage secondary to chronic disseminated intravascular coagulation (DIC) which continued for eight months is described. Despite continuing DIC two major operations were performed without excessive blood loss. Preoperative heparinization, in vitro clotting of the arterial graft, and temporary postoperative reversal of systemic heparin were utilized for abdominal aortic aneurysm resection. Blood product replacement therapy facilitated an emergency laparotomy. The patient was also managed successfully for several months without anticoagulant therapy. A hypothesis that vascular thrombi are not a necessary prerequisite for DIC is proposed. This hypothesis is based on the absence of thrombi or evidence of ischemia in this patient and in others and is supported by experimental observations made by other investigators.