Despite technological advances, the use of homologous blood to prime the cardiopulmonary bypass (CPB) circuits of infants under 10 kg remains common. However, such rapid massive transfusion may increase post-CPB morbidity. We retrospectively included consecutive patients weighing 2.3-10 kg who underwent cardiac surgery under CPB. Patients were divided into two groups based on their priming volumes: low priming volume (LPV) (below the median volume) or high priming volume (HPV) (the median volume or above). The study included 208 patients, of whom 104 had priming volumes below the median [37.9 (28.4-51.7) mL/kg] and 104 had at least the median volume. We recorded positive correlations between the priming volume, on the one hand, and the peak creatinine and CRP levels within 5 days postoperatively, the duration of intensive care unit (ICU) stay, and the mechanical ventilation time, on the other. A relationship was also observed between a higher median priming volume and the need for renal replacement therapy in the ICU and mediastinitis. Although the differences in priming volume between the twogroups were small, they significantly influenced the postoperative complications. Perfusionists should seek to limit the priming volume to reduce the post-CPB inflammatory response, the duration of ICU stay, and possibly the risk of mediastinitis.Read less <