We have attempted to reduce blood use during the perioperative period to avoid complications associated with blood transfusions in pediatric patients undergoing open-heart surgery. We retrospectively reviewed clinical data of patients who underwent open-heart surgery (age < 15 years, body weight ≤ 30 kg) from January 2012 to October 2013. Our strategy to reduce transfusion volume included: (1) shortening the length of cardiopulmonary bypass (CPB) circuit, and adding red blood cells (RBC) to CPB circuit priming solution when preoperative hematocrit was ≤30 %; (2) routine modified ultrafiltration in all patients; and (3) restricting RBC transfusions during postoperative period, given when hematocrit was ≤25 %. In total, 349 cases were enrolled. The median age of patients was 7 months (1 day–168 months), and body weight was 7 kg (2.3–30 kg). We did not use blood products in 81 (23.2 %) cases and did not add RBCs to CPB priming solution in 119 (34.1 %) cases. Patients who did not require a transfusion showed a shorter intensive care unit (ICU) stays (0.97 ± 0.5 days) than patients who required a transfusion (4.1 ± 5.5 days, p = 0.003). Larger volume transfusion correlated with longer intubation durations, ICU and hospital stays, higher peak C-reactive protein levels, and an increased blood urea nitrogen/creatinine ratio. No significant problems were observed in patients with relatively lower hematocrit levels. Our strategy to reduce transfusion volume resulted in shorter ventilator support, ICU stay, hospitalization, reduced inflammatory reaction, and less kidney insult during the postoperative course in pediatric patients.