Patients due to undergo elective surgery who are not considered to be medically fit, may have their operation postponed or even cancelled. Not only will this result in significant anxiety for the person, but it will also have financial implications for the hospital, in terms of lost theatre time. In an attempt to prevent postponing or cancelling scheduled surgery, pre-operative assessment is essential to ensure that the patient is physically and emotionally prepared. This article examines the main components of pre-operative assessment and how addressing any problems before surgery can help to improve post-operative outcomes for patients.