Severity of injury can now be measured objectively and in a manner relevant to everyday practice. A variety of scales/scores are available which are based either on anatomical or physiological parameters or a combination of these. ASCOT methodology represents the most recent major contribution in this area, and follows AIS and TRISS as an established and reliable means of assessing trauma patients, particularly in relation to survival. These methods have clinical application in terms of triage, directing clinical management, assessing prognosis, assessing cost of management and for measuring outcome. The development of these scoring methods is outlined in this paper.