Trained nurses using a rule-based computer program can successfully carry out pre-anaesthesia screening. All medical problems and abnormal laboratory results need to be reviewed by an experienced anaesthetist. Following the introduction of this system, there was a reduction in the frequency of cancellations of patients from elective orthopaedic operating lists from 4.8% to 1.8%, a difference that was statistically significant (p = 0.03, CI = [0.6%, 5.5%]). To minimise cancellations from booked operating lists, a booked admissions policy is essential, so that the anaesthetist who will eventually be responsible for patients with medical problems can be identified. Cancellations cannot be avoided completely because some abnormal conditions arise or deteriorate after completion of the screening process. The anaesthetist responsible for the patient's anaesthetic may have different views of the risks involved from those of the anaesthetist undertaking the screening process.