Objective Intra-operative coagulopathy has a close relationship with blood loss and the prognosis of patients. Rapid-thrombelastography (r-TEG) is a comprehensive assessment of coagulation abnormalities and also an effective way for constructing blood transfusion. This study attempts to investigate the correlation of r-TEG indices with intra-operative hemorrhage.Methods Patients who underwent transphenoidal hypophysectomy and craniotomy from January 15 to April 30, 2013 in Peking Union Medical College hospital were recruited. All patients had pre- and post-operative r-TEG and conventional coagulation tests (CCTs). Patients' information and intra-operative blood loss as a percentage of estimated blood volume were recorded. Spearman's correlation analyses were used for discovering the relationship between indices in r-TEG or CCTs and the intra-operative blood loss. The significant correlated index of r-TEG was further investigated using linear regression analysis. Results A total of 181 patients participated in this study. Intra-operative change of α-angle, which reflects the fibrinogen level and function, was the only r-TEG index that correlated with blood loss significantly (P=0.013, r= -0.184), thus challenging the current empirical cognition of the effects of intra-operative hemorrhage on coagulation. As intra-operative blood loss increased, α-angle decreased, and every 1% loss of estimated blood volume (EBV) led to 0.60 degree decrease of α-angle. As for CCT results, changes of fibrinogen and platelet count were also significantly correlated with blood loss (P=0.015 and P=0.001, respectively).Conclusions Peri-operative change of α-angle, as an index of r-TEG, exhibited a significant negative correlation with intra-operative blood loss. The impact of hemorrhage on fibrinogen, instead of clotting factors, should be scrutinized.