The aim of this study is to evaluate if a simple intra-aortic balloon pump (IABP)-induced pulsatile perfusion reduces activation of coagulative system during cardiopulmonary bypass (CPB). Ninety-six patients undergoing preoperative IABP were randomized to nonpulsatile CPB with IABP discontinued during cardioplegic arrest (Group A) or IABP-induced pulsatile CPB (Group B). White blood cells (WBC), hematocrit (Ht), platelets (PLTs), International Normalized Ratio (INR), fibrinogen, activated partial thromboplastin time (aPTT), antithrombin III (AT-III) activity, and D-dimer were measured at the end of surgery (ES) and postoperatively. Chest drainage, need for reexploration, and transfusions were compared. Group B showed lower chest drainage (1st day P = 0.038; 2nd day P = 0.044), transfusions (P = 0.031), WBC (P < 0.05 at all time points), and INR (P < 0.05 at all time points), together with a higher Ht (P < 0.05 at ES, 12 h), platelets (P < 0.04 at all time points), fibrinogen (P < 0.05 at ES, 12 h, 24 h), and aPTT (P < 0.05 at all time points). AT-III activity lowered in Group A (P = 0.001 at ES, 12 h, 24 h), together with higher D-dimer levels (P < 0.05 at all time points). IABP-induced pulsatile perfusion ameliorates coagulative system activation following CPB.