The quantity of blood products used perioperatively during cardiac surgery is known to vary widely between institutions. This study looked at the amount of blood products used perioperatively in 74 consecutive elective cardiac operations in one institution. The results are compared with those from other European centres and a cost analysis carried out. On average 2.33 +/- 0.74 (95% confidence interval 1.93-2.77) units of red cell concentrate were transfused perioperatively per patient. Six (8%) patients received no blood products. In addition a number of preoperative factors were studied in an attempt to identify predictors of transfusion requirements. Age, preoperative haemoglobin, female sex and red cell mass were all found to have some predictive value. In the face of increasing demands on a limited supply of blood products we question the need for cross matching more than four units of red cell concentrate in elective cardiac surgery.