Abstract Background and objective Prediction of postoperative excessive blood loss is useful for management of Intensive Care Unit after cardiac surgery. The aim of present study was to examine the effectiveness of International Society on Thrombosis and Hemostasis scoring system in patients with cardiac surgery. Method After obtaining approval from the institutional review board, the medical records of patients undergoing elective cardiac surgery using Cardio-Pulmonary Bypass between March 2010 and February 2014 were retrospectively reviewed. International Society on Thrombosis and Hemostasis score was calculated in intensive care unit and patients were divided with overt disseminated intravascular coagulation group and non-overt disseminated intravascular coagulation group. To evaluate correlation with estimated blood loss, student t-test and correlation analyses were used. Results Among 384 patients with cardiac surgery, 70 patients with overt disseminated intravascular coagulation group (n = 20) or non-overt disseminated intravascular coagulation group (n = 50) were enrolled. Mean disseminated intravascular coagulation scores at intensive care unit admission was 5.35 ± 0.59 (overt disseminated intravascular coagulation group) and 2.66 ± 1.29 (non-overt disseminated intravascular coagulation group) and overt disseminated intravascular coagulation was induced in 29% (20/70). Overt disseminated intravascular coagulation group had much more EBL for 24 h (p = 0.006) and maintained longer time of intubation time (p = 0.005). Conclusion In spite of limitation of retrospective design, management using International Society on Thrombosis and Hemostasis score in patients after cardiac surgery seems to be helpful for prediction of the post- cardio-pulmonary bypass excessive blood loss and prolonged tracheal intubation duration.