The utility of the Abbreviated Injury Scale (AIS), the most widely used anatomic scale for rating severity of injuries, and its derivative for assessing the combined effect of multiple injuries, the Injury Severity Score (ISS), were tested for their ability to predict functional disability at time of discharge from the hospital and 6 months after discharge. The ISS has been shown to correlate well with mortality and length of stay, but the relationship to levels of subsequent disability has not been examined. Five hundred and ninety-seven patients (aged 16-45 years) were interviewed at time of discharge and 6 months after discharge to ascertain functional disability along three dimensions: activities of daily living (ADL), instrumental activities of daily living (IADL), and mobility. The authors report on the relationship between severity and functional disability at time of discharge and 6 months after discharge for a subset of 473 patients who did not suffer a severe brain injury. The results show that the relationship between ISS and status at discharge and 6 months after discharge is not monotonically increasing, as it is with mortality and length of stay (LOS). Rather, the proportion of people with severe injuries who report limitations is lower than for those with moderately severe injuries as defined by the ISS. Further, it is shown that the AIS of the most severe extremity and spinal cord injury carry considerably more weight when predicting functional status at discharge and 6 months after discharge than do the AIS scores of injuries to any other body region, although the relative explanatory power of each type of injury varies with the nature of the functional disability and the time interval between the initial insult and assessment.