['Efforts to reduce blood product use have the potential to avoid transfusion-related complications and reduce health care costs. The purpose of this investigation was to determine whether a multi-institutional effort to reduce blood product use affects postoperative events after cardiac surgical operations and to determine the influence of perioperative transfusion on risk-adjusted outcomes.', 'A total of 14,259 patients (2006-2010) undergoing nonemergency, primary, isolated coronary artery bypass grafting operations at 17 different statewide cardiac centers were stratified according to transfusion guideline era: pre-guideline (n = 7059, age = 63.7 ± 10.6 years) versus post-guideline (n = 7200, age = 63.7 ± 10.5 years). Primary outcomes of interest were observed differences in postoperative events and mortality risk-adjusted associations as estimated by multiple regression analysis.', 'Overall intraoperative (24% vs 18%, P < .001) and postoperative (39% vs 33%, P < .001) blood product transfusion were significantly reduced in the post-guideline era. Patients in the post-guideline era demonstrated reduced morbidity with decreased pneumonia (P = .01), prolonged ventilation (P = .05), renal failure (P = .03), new-onset hemodialysis (P = .004), and composite incidence of major complications (P = .001). Operative mortality (1.0% vs 1.8%, P < .001) and postoperative ventilation time (22 vs 26 hours, P < .001) were similarly reduced in the post-guideline era. Of note, after mortality risk adjustment, operations performed in the post-guideline era were associated with a 47% reduction in the odds of death (adjusted odds ratio, 0.57; P < .001), whereas the risk of major complications and mortality were significantly increased after intraoperative (adjusted odds ratio, 1.86 and 1.25; both P < .001) and postoperative (adjusted odds ratio, 4.61 and 4.50, both P < .001) transfusion. Intraoperative and postoperative transfusions were associated with increased adjusted incremental total hospitalization costs ($4408 and $10,479, respectively).'] Is blood product conservation associated with improved outcomes and reduced costs after cardiac surgery?