Abstract Background “Flat-line” (no clot formation) thromboelastography (TEG) is frequently observed after graft reperfusion during liver transplantation (LT). We aimed to evaluate the incidence and causes of flat-line TEG after graft reperfusion during LT. Methods With institutional review board approval, data of 208 consecutive recipients who underwent LT from May 2010 to May 2012 were retrospectively reviewed. We performed 3 different types of TEG measurements at 5 minutes after graft reperfusion: native TEG (nTEG), tranexamic acid–added TEG (tTEG), and protamine-added TEG (pTEG). The flat-line TEG was defined as having no trace at all at 60 minutes of TEG. We examined the incidence and causes of flat-line nTEG. We also compared recipients with flat-line nTEG (F group) and clot-forming nTEG (C group). Results One hundred eighty-two recipients were included in the final analysis. The incidence of flat-line nTEG was 27% (49/182 cases). Among 49 recipients in the F group, 28 recipients showed clot formation in both tTEG and pTEG, 19 recipients in only tTEG, and 1 recipient in only pTEG; 1 recipient showed no clot formation in any TEGs. Graft from the deceased donor was more frequently observed in the F group than in the C group ( P  = .039). The F group showed decreased platelet count ( P  = .001), increased prothrombin time ( P  = .002), and decreased fibrinogen ( P  = .009) compared with the C group. Conclusions No clot formation was relatively common after reperfusion during LT, and the main causes were hyperfibrinolysis and heparin effect. Liver graft from deceased donors was associated more frequently with no clot formation after reperfusion during LT.