In this double-blind, prospective, controlled study the efficacy of aprotinin and tranexamic acid is compared. Primary outcome is the 24 hours postoperative drainage blood loss and the percentage of patients requiring allogeneic blood transfusion during the hospital stay. Subgroups of patients undergoing CABG surgery or aortic valve replacement are predefined for combined and separate data analysis.The power of the study is calculated for this subgroup-analysis.