Cancer patients undergoing surgery often present with unusual and challenging problems. Their age and the fact that they are often chronically ill place them at increased surgical risk. In many instances the need for surgical intervention is crucial to the extent that risk-assessment becomes an academic issue, especially for those patients whose only reasonable chance for either cure or palliation of unbearable disease is surgery. However, the internist's role in these situations often has preoperative, intraoperative, and postoperative ramifications. Preoperatively, the internist assesses operative risk and intervenes, when possible, to reduce the likelihood of surgical complications. Patients who clearly cannot survive surgery may be identified and channeled to other treatment modalities. Intraoperatively, the internist may be called upon to help with the management of acute organ failure, cardiac arrest, or vascular collapse. Following surgery, the internist may help by managing cardiopulmonary problems and treating infectious complications. The critical care internist is therefore an important member of the perioperative team and often provides valuable expertise, which can help to identify and treat problems expediently.