The most important complications following gastrointestinal surgery are related to disruption of anastomoses. The fate of a gastrointestinal anastomosis is influenced by many factors. Among these, care in the anaesthetic management and postoperative treatment may reduce the incidence of complications. There are two major directions in which such care may be aimed. The prevention of high intra-luminal pressures and excessive longitudinal traction across anastomoses may be aided by care in the administration of neostigmine, and possibly by the avoidance of morphine for provision of intra-operative and postoperative analgesia. Maintenance of, or improvements in, oxygen supply to an anastomosis may be achieved by avoiding hypoxia, hypocapnia and hypovolaemia, and by the use of regional anaesthetic techniques during surgery and/or in the post-operative period. In addition, sedative and analgesic therapy may influence the incidence of postoperative ileus, and may thus contribute to morbidity.