A patient with chronic idiopathic thrombocytopenic purpura (ITP), chronic disseminated intravascular coagulation (DIC) and abdominal aortic aneurysm is described. He had severe thrombocytopenia and his platelet life span was shortened (29 h). Indium 111-labeled platelet scintigraphy demonstrated an increased accumulation of radioactivity over the aneurysm and the spleen. Following preoperative heparin therapy for DIC, the platelet count remained low (10 × 109/l), while the DIC improved. Because of the elevated platelet-associated IgG, we considered that the patient had complicated chronic ITP. After intravenous immunoglobulin therapy, his platelet count increased. The aneurysm was successfully replaced with an artificial Y-graft vessel and a splenectomy was performed at the same time. The platelet count was maintained at about 60 × 109/l after the operation and the patient is quite well now.