BACKGROUND: Endogenous heparinoid substances have been mentioned as one of the causes of coagulopathy during liver transplantation. Some reported that heparin effects after reperfusion increase with decreasing liver function, as assessed by the Child-Pugh classification. Comparisons of native and heparinase TEG can assess the quantity of heparin effects and distinguish the cause of coagulopathy. We investigated the heparin effects before reperfusion by heparinase-guided TEG and the correlation between heparin effects and the UNOS and Child-Pugh score. METHODS: 67 liver transplanted patients were studied and divided two groups. Two groups were control group that exist heparin effect and experimental group that does not exist heparin effect during preanhepatic period. Native and heparinase TEG are performed simultaneously after anesthetic induction. Present heparin effects were defined as coagulation time (gamma + kappa) differs more than 20% between native and heparinase TEG showing the native TEG's index is out of the normal range. RESULTS: Heparin effects were present before reperfusion in 29.8% of liver transplantation cases and these were related more with the Child-Pugh classification than UNOS (gamma = 0.31, P = 0.012). There were many transfusions of packed red cells and a large infusion amount through RIS in the group with heparin effects but there was no statistical significance. CONCLUSIONS: We could confirm that heparin effects appear already before reperfusion in 29.8% of the cases using heparinase-guided TEG and this correlates with the Child-Pugh classification