AIM:To study the effect of aprotinin used in orthotopic liver transplantation (OLT) on the intraoperative requirement for blood products and on the incidence of laparotomy for bleeding,thrombotic events and mortality.METHODS:A systematic review of the literature in the electronic database Medline and the Clinic Trials Registry Database was performed.Literature that did not fit our study were excluded.Patients in the reviewed studies were divided into two groups; one group used aprotinin (aprotinin group) while the other did not (control group).The data in the literature that fit our requirements were recorded.Weighted mean differences (WMD) in the requirements for blood products between the aprotinin group and the control group were tested using a fixed effect model.A Z test was performed to examine their reliability; the Fleiss method of fixed effect model was used to analyze data on postoperative events,and odds ratios (ORs) were tested and merged.RESULTS:Seven citations were examined in our study.Among them,a requirement for blood products was reported in 4 studies including 321 patients,while postoperative events were reported in 5 studies including 477 patients.The requirement for red blood cells and fresh frozen plasma in the aprotinin group was statistically lower than that in the control group (WMD = -1.80 units,95% CI,-3.38 to -0.22; WMD = -3.99 units,95% CI,-6.47 to -1.50,respectively).However,no significant difference was indicated in the incidence of laparotomy for bleeding,thrombotic events and mortality between the two groups.Analysis on blood loss,anaphylactic reactions and renal function was not performed in this study due to a lack of sufficient information.CONCLUSION:Aprotinin can reduce the intraoperative requirement for blood products in OLT,and has no significant effect on the incidence of laparotomy for bleeding,thrombotic events and mortality.