In an animal experimental model the survival of untreated red blood cells (RBC) tagged with 51Cr was compared with cells processed by an autotransfusion device separating and washing the RBC tagged with 111In. Intraoperative autotransfusion (IAT) was done by the Haemonetics Cell Saver. Additionally the morphology of human RBC was investigated in different stages of IAT by the aid of scanner electron micrographs. The survival of RBC after processing was slightly decreased in comparison to untreated cells. The morphology of autologous RBC is little affected compared with older homologous RBC in erythrocytic concentrates. Cell detritus due to haemolysis is reliably eliminated by microfiltration. Especially regarding survival and morphologic alterations of RBC IAT with a system separating and washing the cells seems to be superior to the transfusion of homologous blood.