This study was conducted to investigate whether rapid and efficient administration of blood products was achieved and whether clinical outcomes were improved by applying a massive transfusion protocol (MTP). methods: From January 2016 to September 2019, the medical records of trauma patients who received at least 10 units of packed red blood cells (PRBC) at Pusan National University Hospital (level I trauma center) were retrospectively reviewed. The patients treated from January 2016 to January 2018 were designated as the non-MTP group, and those treated from February 2018 to September 2019 were designated as the MTP group. results: During the study period, 370 patients received massive transfusions. The non-MTP and MTP groups comprised 84 and 55 patients, respectively. No significant between-group differences were found in the units of PRBC (23.2 vs. 25.3, respectively; p=0.46), fresh frozen plasma (FFP) (21.1 vs. 24.4, respectively; p=0.40), and platelets (PLT) (15.4 vs. 17.0, respectively; p=0.54) administered in the first 24 hours. No statistically significant differences between the non-MTP and MTP groups were found in the FFP-to-PRBC ratio (0.9 vs. 0.94, respectively; p=0.44) and or the PLT-to-PRBC ratio (0.72 vs. 0.72, respectively; p=0.21). However, the total number of cryoprecipitate units was significantly higher in the MTP group than in the non-MTP group (7.4 vs. 15.3 units, respectively; p=0.003) and the ratio of cryoprecipitate to PRBC in the MTP group was significantly higher than in the non-MTP group (0.31 vs. 0.62, respectively; p=0.021). The time to transfusion was significantly reduced after MTP implementation (41.0 vs. 14.9 minutes, respectively; p=0.003). Conclusions: Although no significant differences were found in the clinical outcomes of patients who had undergone severe trauma, rapid and balanced transfusion was achieved after implementing the MTP.