A huge number of surgical procedures are carried out annually. Although estimates of mortality and morbidity vary, they are generally accepted to be significant in high-risk patients. It is important to identify and optimize these patient groups before proceeding with surgery. Furthermore, accurate estimates of the risk of both mortality and morbidity in individual patients should be carried out in order to obtain valid consent. Once in theatre, a number of evidence-based interventions are undertaken to ensure optimal outcomes, with the aim of both restoring normal physiology and ensuring that postoperative recovery is as smooth as possible.