Patients with preoperative demographic data such as age, gender, body weight, height, and additional disease, medications, previous surgery, preoperative Htc / Hb values were recorded in the operation room without medical premedication. Standard anesthesia induction was performed after arterial cannulation and peripheral venous route. Patients were randomly divided into two groups: 400 IU heparin / kg (Group I) and 400 IU heparin / kg (Group II) according to actual body weight and lean body weight respectively before CPB. Before and after heparin administration, CPB entry and ACT (Activated Clotting Time) values were counted every 30 minutes, after CPB exit and protamine. In both groups, supplemental heparin was administered when there was a failure to reach the pre-CPB target ACT value of 400 sec. Hemodynamic data and transfusion requirements were recorded during the operation. Patient's intraoperative CPB and crossover times, postoperative drainage volume and blood transfusion requirement were recorded.