Purpose: Cardiothoracic surgeons and anesthesiologists have had a long-standing interest in the proper use of transfusion therapy for their patients. Source: We review the literature on variability and patterns of transfusion practices in cardiac surgery, on the infectious and noninfectious risks of transfusions, and on the impact of new technologies. Data from the cardiac surgery registry at the Beth Israel Deaconess Medical Center are presented. Principal findings: Blood conservation strategies such as intraoperative and postoperative salvage, hemodilution and drug treatments to minimize bleeding were developed for cardiac patients. Despite this work, there is significant variation in transfusion practices among cardiac surgery centers. improved donor selection and screening by increasingly sophisticated tests have dramatically reduced the risks of transfusion-transmitted disease. However, the increasing acuity and complexity of the condition of patients having surgery, as well as the availability of safer allogeneic blood, have resulted in an increasing number of transfusions to patients undergoing cardiac operations. The majority of patients having open heart surgery receive allogeneic blood. Blood conservation strategies continue to be important because of the non-infectious hazards of transfusion such as mistransfusion, transfusion-related acute lung injury, circulatory overload and others. Newer technologies (such as minimally invasive and off-pump surgery) promise to favourably affect blood use. Conclusion: Issues such as the cost of blood, limited availability and the potentially harmful effects of transfusion dictate continued research and the development of methods to appropriately minimize transfusion to patients having cardiac surgery.