In spite of multiple technical advances, large amount of homologous blood transfusions usually required for open heart surgery. Because the complications associated with transfusion are increased as the number of homologous transfusion increase, especially as transfusion related acquired immunodeficiency syndrome has appeared in recent years, such risks have stimulated recent interest in the use of autologous blood. This is a report concerning 23 consecutive adult autologous donors[autologous group] who had elective cardiac surgery at the Yonsei Cardiovascular Center, Yonsei University College of Medicine, from march, 1990 to august, 1991. A similar group of 23 patients operated during the same periods without autologous blood donation was used for comparison [control group] to investigate the effect of predonated autologous blood in decreasing the need of homologous transfusion and to investigate predonation related adverse effect. Autologous group consisted of 15 men and 8 women. Control group consisted of 7 men and 16 women. There were no significant differences in mean age, hemoglobin, hematocrit, RBC count, platelet count and prothrombin time on admission between the two groups. The mean autologous blood donation in autologous group was 2.2 units. In 10[43.5%] of the 23 atuologous group patients, no homologous RBC products transfusion was required. However, all patients required homologous transfusion in control group. In autologous group, patients required less homologous RBC products than control patients[2.1 units versus 5.3 units; p<0.001]. There were no significant differences in hemoglobin, hematocrit, RBC count and platelet count between the two groups before discharge. There were no serious complications related to preoperative blood donation, although 3 patients complained of mild dizziness during donation We conclude that preoperative autologous predonation of blood is a safe and effective method for reducing homologous transfusion and is recomended in all patients undergoing elective cardiac surgery except limited contraindications such as severe aortic valve stenosis or unstable angina pectoris.