Abstract Objective: To correlate blood transfusions and clinical outcomes during hospitalization in coronary artery bypass grafting surgery (CABG). Methods: Transfusion, clinical and hematological data were collected for 1,378 patients undergoing isolated or combined CABG between January 2011 and December 2012. The effect of blood transfusions was evaluated through multivariate analysis to predict three co-primary outcomes: composite ischemic events, composite infectious complications and hospital mortality. Because higher risk patients receive more transfusions, the hospital mortality outcome was also tested on a stratum of low-risk patients to isolate the effect of preoperative risk on the results. Results: The transfusion rate was 63.9%. The use of blood products was associated with a higher incidence of the three coprimary outcomes: composite infectious complications (OR 2.67, 95% CI 1.70 to 4.19; P<0.001), composite ischemic events (OR 2.42, 95% CI 1.70 to 3.46; P<0.001) and hospital mortality (OR 3.07, 95% CI 1.53 to 6.13; P<0.001). When only patients with logistic EuroSCORE ≤ 2% were evaluated, i.e., low-risk individuals, the mortality rate and the incidence of ischemic events and infectious complications composites remained higher among the transfused patients [6% vs. 0.4% (P<0.001), 11.7% vs. 24,3% (P<0.001) and 6.5% vs. 12.7% (P=0.002), respectively]. Conclusion: The use of blood components in patients undergoing CABG was associated with ischemic events, infectious complications and hospital mortality, even in low-risk patients.