The value of the TRISS method for interhospital comparisons of trauma care was studied using data for 5,616 consecutive patients from three trauma centers and five community hospitals. Z-scores were used to compare mortality rates. Three limitations of the method were documented: 1) the lack of homogeneity within the patient subcategory of penetrating injuries, specifically between patients with gunshot versus stab wounds; 2) the inability of the TRISS method to predict the survival rate of patients suffering low falls; and 3) the inability of the TRISS method to account for multiple severe injuries to a single body part. Remedies to the first two of these limitations can be addressed within the present TRISS method. A remedy for the third requires a new method.