This paper describes a computerized conversion table which maps discharge diagnoses coded using the Clinical Modification of the 9th Revision of the International Classification of Diseases (ICD-9CM) into 1985 Abbreviated Injury Scale (AIS) scores. The development of the table is described in detail with major assumptions used in conversion of ICD to AIS discussed. In consultation with the AAAM Injury Scaling Committee, 1948 of the 2072 injury related ICD-9CM rubrics were assigned valid AIS scores between 1 and 6. The remaining 124 rubrics were assigned AIS scores of 9, either because the ICD description lacked sufficient qualifying information for determining severity or because injuries of very different levels of severity were incorporated within a single diagnostic rubric. The application of the conversion system using uniform hospital discharge abstract data is illustrated by two examples relevant to the management and evaluation of regionalized trauma systems.