Background: One of the typical problems of cell savers is the retransfusion of the heparin added to the system. The aim of this study was to determine whether or not heparin, remaining in the prepared sample of retransfusion blood, might be responsible for disturbance in coagulation and increase in blood loss.Methods: Fifty patients undergoing coronary artery bypass grafting surgery (CABG) were randomly divided into two groups: group C (n=25) received cell-saver blood and group H (n=25) received homologous blood. Volumes of the intraoperative autologous and homologous transfusion, activated clotting time (ACT) of the transfused bloods, and ACT and amount of blood loss in the patients were measured intra and postoperatively.Results: There was no statistical difference between the groups in terms of demographics, preoperative characteristics, or operative details. Cell saver was used in 25 cases, and the average volume of blood autotransfused was 504±158 mL. A significant statistical difference was observed in the mean volumes (460±200 vs.80±160 mL; P=0.0001) of perioperative allogeneic blood transfusions between groups H and C. Despite significant further cell-saver blood transfusion (504±158 cc vs.338±123 cc; P=0.001) and a significantly longer ACT of cell-saver blood than homologous blood (959±85 sec vs.478±58 sec; P=0.0001) intraoperatively, there was no significant difference between the two groups in terms of postoperative blood loss (510±270 cc in group H vs.454±150 cc in group C; P=0.362).Conclusion: Utilization of a cell saver was safe, with no increased risk of bleeding despite heparin added to the system.