Due to the growing importance of quality assurance and cost containment in healthcare, eliciting patients' preferences for post-operative outcomes may be a more economical and reliable method of assessing quality. Three hundred and fifty-five day surgery patients completed a pre-operative written questionnaire to identify patients' preferences for avoiding 10 particular post-operative symptoms: pain, nausea, vomiting, disorientation, shivering, sore throat, drowsiness, gagging on the tracheal tube, thirst and a normal outcome. The two scoring methods used to evaluate preferences were priority ranking and relative value scores. The effects of age, gender, previous health status, type of surgery and previous experience of anaesthesia on patients' preferences were also examined. Avoiding post-operative pain, gagging on the tracheal tube and nausea and vomiting are major priorities for day-case patients. Anaesthetists should take patients' preferences into consideration when developing guidelines and planning anaesthetic care.