MDCO-2010, a synthetic small molecule, is a direct inhibitor of plasmin and plasma kallikrein. Both of these have been implicated with impaired haemostasis. In addition, potent inhibition of coagulation factors Xa, XIa and activated Protein C has been demonstrated. Thus, MDCO-2010 has the potential to mitigate excessive fibrinolysis and thrombin generation during cardiac surgery involving a cardiopulmonary bypass. In particular the latter is supposed to provide additional benefits beyond reducing transfusion requirements.