Ten patients with abdominal aortic aneurysms and ten with aortoiliac occlusive disease underwent aortic resections with use of intraoperative autotransfusion. Results were compared with 20 similar patients in whom conventional transfusion techniques were used. An average of 1.5 liters of blood was aspirated, filtered, and reinfused per patient; half of the patients received no homologous blood during surgery. Hematocrit level fell, and free plasma hemoglobin was transiently elevated in all patients. Despite the potential alterations in clotting factors and blood elements, intraoperative autotransfusion appeared to be useful in providing a hepatitisfree, readily available source of blood during difficult aortic resections.