Abstract: We evaluate the effect of topical application of aprotinin to the heart, pericardia and mediastinum before sternal closure, on early post operative bleeding, blood transfusion requirement and ICU staying time after coronary artery bypass graft surgeries. In a randomized double blinded clinical trial, 128 patients who were scheduled for elective coronary artery bypass graft were allocated into two groups. In group A (aprotinin), patients received 500,000KIU (50 mL) aprotinin and in group S (saline group) the same volume of normal saline was applied. The amount of blood loss collected in chest bottle, the number of pack cells requirement during first 24 h after operation and duration of ICU staying time were recorded. The amount of blood loss in group A (aprotinin) was 451±218 mL compared with 707±269 mL in group S (saline) (p = 0.003). The number of pack cells consumption was 0.5±0.7 units in group A (aprotinin) compared with 1.7±1 units in saline group (p = 0.002). Intensive Care Unit (ICU) staying time was 48.8±13.6 h in group A(aprotinin) and 69.4±16.6 h in saline group (p = 0.001). This study showed that topical application of aprotinin at the end of coronary artery surgeries, significantly reduce postoperative bleeding and blood transfusion requirement during first 24 h after operation and also ICU staying time.