Objective: Plasma free-hemoglobin (PF-Hb) is a major risk factor of postoperative acute kidney injury (AKI) in pediatric cardiac surgery with cardiopulmonary bypass (CPB). This study aimed to evaluate our method of intraoperative haptoglobin administration. Methods: This retrospective study enrolled patients who underwent pediatric cardiac surgery with CPB at Kobe Children’s Hospital from May 2016 to February 2020. They were divided into two groups according to intraoperative haptoglobin administration based on the presence of macroscopic hematuria (Group C) or on the levels of PF-Hb, circulating blood volume and prime volume of the CPB circuit (Group P). To adjust for potential baseline confounders, propensity score matched analysis was performed for a selection of 81 patients in each group. Perioperative variables were compared between the two groups. Results: According to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, stages Ⅱ and Ⅲ were observed in 16 and 5 patients in Group C and P, respectively. The incidence of postoperative AKI in Group P was significantly lower than that in Group C (22% vs 43%, P = 0.0071). Postoperative increase in serum creatinine level from the preoperative baseline level was significantly smaller in Group P as compared with that in Group C. Conclusions: Intraoperative haptoglobin administration strategy, based on PF-Hb level, circulating blood volume and prime volume of the CPB circuit in each patient, has the possibility of reducing the postoperative AKI.