Transfusion after cardiac surgery is very common. This rate varies between institutions and has remained high despite established transfusion guidelines. We analyzed our database of patients who underwent isolated CABG (Coronary Artery Bypass Graft) to determine the predictive factors of homologous transfusion and associated postoperative morbidity, mortality and resource utilization. All 14,152 patients who underwent first-time isolated CABG, with or without cardiopulmonary bypass (CPB) who had postoperative homologous transfusion between February 2002 and March 2008 in Tehran Heart Center, were evaluated retrospectively. Overall, 16.5% of patients received transfusion. Transfused patients demonstrated a significantly higher incidence of postoperative complications (cardiac, infectious, ischemic, reoperation) and mortality (p<0.001). Homologous blood transfusion effect on mortality, morbidity and resource utilization. By Multivariable logistic regression analysis adjusted for confounders: Homologous blood transfusion effect on Mortality (30-days) (OR=3.976, p<0.0001), Prolonged ventilation hours (OR=4.755, p<0.0001), Total ICU hours (β =14.599, p<0.0001), Hospital length of stay (β =1.141, p<0.0001), Post surgery length of stay (β =0.955, p<0.0001). We conclude that the isolated CABG patients receiving blood transfusion have significantly higher mortality, morbidity and resource utilization. Homologous blood transfusion is an independent factor of increased resource utilization, morbidity and mortality.