Bleeding is a common post-operative phenomenon after cardiac surgery and in some circumstances can be severe enough to warrant emergency re-exploration. This is a high-risk intervention owing to the haemodynamic instability of the patient, ischaemic injury from end-organ hypoperfusion and deleterious effects of excessive blood product transfusion. This chapter aims to provide a comprehensive overview of the predictors and causes of bleeding after cardiac surgery, potential bleeding sources at re-exploration, indications and optimal timing for re-exploration, surgical technique for re-sternotomy, prognostic and economic implication of re-exploration and strategies to minimise excessive bleeding and re-exploration.