Aim: Post-operative bleeding remains a significant risk after cardiac surgery. Despite adequate protamine reversal of heparin intraoperatively, protein-bound heparin causes anticoagulant effect, leading to bleeding in the post-operative period. The aim of this study is to whether the use of a four-hour, low dose protamine infusion in intensive care would reduce post-operative bleeding and hence, blood transfusion requirements. Methods: A retrospective cohort study of seven hundred and two patients, who underwent elective or urgent coronary artery bypass grafting from April 2014 and January 2017, were divided into two groups based on who received post-operative protamine infusion (Group A, 472 patients) versus those who did not (Group B, 230 patients). They were assessed for amount of post-operative mediastinal and pleural drainage for the first 24 hours, use of post-operative transfusion of blood products, postoperative hospital stay, and re-exploration. Results: We found no significant difference between the rate of bleeding in either of the groups. No significant difference was observed in blood product requirements as well. In the sub-group consisting of patients with high BMI (BMI ≥30), who received protamine infusion, post-operative platelets transfusion was found to be significantly less. Conclusions: Our results suggest that a low dose protamine infusion given in the immediate postoperative period does not lead to any significant clinical benefits. Both patients receiving and not receiving the infusion had similar postoperative drainage, transfusion requirements, haemorrhagic morbidity, mortality and length of hospital stay.