The Abbreviated Injury Scale (AIS) introduced in January 1968 has been widely used by the Medical Engineering Accident Investigation Teams of the NHTSA, by the General Motors ADAP, by the NATO Country Teams in Europe, and by the AMA Physician-Police Teams. The experience and problems involved in use of the AIS are reviewed. An extended and revised AIS has been developed. Validation studies revealed better than 80% accuracy by multiple users.The Comprehensive Research Injury Scale (CRIS) has been completed for all major medical specialties. The CRIS separates the various criteria (energy dissipation-ED, threat to life-TL, permanent impairment-PI, treatment period-TP, incidence-IN) used with variable quantities and frequencies in the AIS. The CRIS identifies and quantitates each scaling criteria permitting more meaningful and detailed application of the AIS.AIS WAS INTRODUCED in January 1968 to provide a more definitive classification system for traumatic injuries, particularly those caused by automobile collisions. The introduction coincided with the establishment of the Multidisciplinary Accident Investigation teams (MDAIT) by the U.S. Department of Transportation. It was essential to permit comparative analysis of the cases submitted by the different MDAIT. Since then the AIS has been widely used without modification throughout the United States and Europe.