The problems of anaesthetizing ill patients with intestinal obstruction arise from the possibility of aspirating stomach contents, and from attempts to produce adequate abdominal muscular relaxation. The hazards and mechanisms of both vomiting and regurgitation are discussed in detail. On this basis, the rationale of preventing aspiration is described. For the production of adequate abdominal relaxation, the muscle relaxants appear to be the method of choice, despite occasional abnormal responses in these patients. The nature of these responses and methods of rendering them even less common are discussed in detail.