Background. A retrospective study was conducted at a university hospital to determine the efficacy of conjugated estrogen in reducing blood product transfusion during orthotopic liver transplantation. Methods. The charts of patients who had orthotopic liver transplantation were retrospectively reviewed. Only those having a reaction time > 30 mm or 15 minutes (normal = 19 mm to 28 mm) on computerized thromboelastogram (CTEG) at the beginning of surgery were included. One group of patients received a first dose of conjugated estrogen (100 mg IV) at the beginning of the case and a second dose (100 mg IV) just after reperfusion of the new graft. The control group did not receive estrogen. The two groups were similar in age, weight, first TEG measurements, final intraoperative hemoglobin concentration and platelet count. Blood products were given in response to hematocrit and CTEG measurements, which were determined every hour during surgery. Results. The two groups did not differ in units of cryoprecipitate and platelets administered, but the intraoperative requirements for red blood cells and fresh frozen plasma were significantly lower in the estrogen group than in the control group. Conclusion. Administration of conjugated estrogen is associated with a statistically significant decrease in use of red blood cells and fresh frozen plasma during orthotopic liver transplantation.