Objectives Cardiopulmonary bypass is necessary for surgical repair of complex congenital heart disease. We studied whether whole blood use in circuit prime and for initial intraoperative transfusion needs improved postoperative outcomes in infants less than 2 months of age. Methods Single center retrospective chart review of infants who underwent cardiac surgery utilizing cardiopulmonary bypass between May 2019 and February 2023. We reviewed and analyzed intra and postoperative variables for whole blood and standard blood prime patients while the remainder of clinical management stayed unchanged. Results Ninety-five patients were included in our analysis. Donor exposure was reduced in the whole blood group with a median of 3 donors (Q1-Q3: 2-4) compared to the standard group with 5 donors (Q1-Q3: 5-6, p <0.001). The whole blood cohort utilized whole blood for intraoperative transfusion needs over individual blood components. Whole blood recipients had lower postoperative platelet...