Blood loss was reduced from 325.0±33.1 ml to 175.8+16.2 ml; p<0.0005 (mean ± standart error of the mean) with Aprotinin therapy. And the need for blood transfusion was reduced from 4.3±0.4 U. to 2.4+0.2 U; p<0.0001 (mean ± standart error of the mean). The protease inhibitor, aprotinin therapy reduced postoperative blood loss and therefore the routine application of aprotinin during coronary artery surgery is to be recommended.