A series of 283 patients undergoing cardiac bypass surgery was studied to determine whether intraoperative autotransfusion, haemodilution, and a change in transfusion techniques of the same surgical team could reduce homologous blood requirements. The Cell-Save Haemonetics* system was used systematically in 167 consecutive patients (Group I). This group of autotransfused patients was analysed prospectively and compared with a control group (Group II) of 116 patients operated one year before and analysed retrospectively. During the whole hospitalisation, homologous blood products were required in 40.7% of patients in Group I compared with 73.3% of patients in Group II (p less than 0.0001). The average requirements of packed cells per patient were 2.7 +/- 1.3 in Group I compared with 4.1 +/- 2.5 in Group II (p less than 0.0001). The haematocrit on discharge from the department was 29.9 +/- 4% in Group I compared with 32 +/- 4.5% in Group II (p less than 0.0001). The average volume of blood recovered by the system and then autotransfused was 620.8 +/- 242.6 ml. There was no significant difference in postoperative bleeding in the first 24 hours between the two groups. This study confirms that peroperative autotransfusion during cardiac surgery and the acceptance of a clinically well tolerated normovolumic anaemia are associated with a significant reduction in homologous blood consumption.