Intraoperative autotransfusion using the Bentley ATS 100 was used in 23 patients requiring Dacron replacement of their abdominal aorta. An average 2000 ml of blood was reinfused and a total heparinization dose was given. The mean haemoglobin fell 2.8 g/dl and on average 2 pints of banked blood were given in the postoperative period. Coagulation studies performed before and after surgery showed minimal alteration. We feel that further evaluation of this system is essential so that an alternative is established for when banked blood is not available. The system is particularly useful at the present time for such emergencies as a leaking abdominal aortic aneurysm and severe trauma to the liver.