The development of Condensed Abbreviated Injury Scaling (CAIS) charts (based on AIS-85) has allowed the development of a method to perform early prospective clinical injury scoring (ISS). This information, when available within hours of admission, has allowed an awareness of the magnitude of injuries and creates an appropriate atmosphere for clinical management. In addition, ISS may be used as a rough guide to length of stay and the cost of care for the trauma patient. Three hundred thirty-seven patients entering a Level I Trauma Center were prospectively scored on a daily basis to determine the relationship between time following admission and accuracy. Overall, 18 patients (4.9%) required subsequent changes in their Injury Severity Scores after 24 hours. Patients having severe injury (ISS greater than 16) from blunt trauma had a higher likelihood of having "delayed" diagnosis that resulted in a slightly higher ISS. Overall, the accuracy of this scoring technique was 95% at 24 hours, 98% at 72 hours, and 99% at 5 days.