The field triage guidelines have been widely implemented in the Korean trauma system. This study aimed to evaluate and validate whether it is reliable to use the field triage guidelines for predicting severe traumatic brain injury (TBI) and traumatic spinal injury (TSI) patients. This study retrospectively analyzed in-hospital cohort registries of all TBI and TSI patients, who visited the emergency department (ED) of the Jeju National University Hospital from 1 January 2013 to 31 December 2015. The primary outcome was defined as TBI and TSI patients with an injury severity score (ISS)>15. Secondary outcomes were defined as cases in which one or more of the following conditions: in-hospital death, ISS>15, admission to the intensive care unit, emergency surgery. We enrolled 14,889 TBI and TSI patients who visited ED, of which 7,966 (53.5%) were triage positive. The overall sensitivity, specificity and area under the curve (AUC) of the full cumulative field triage guidelines step's model (Step 1+3+4 criteria) for primary outcome were 82.8%, 47.0%, and 0.646, respectively. In the results for secondary outcomes, the specificity did not show a significant difference, but the sensitivity decreased to 66.5% and AUC to 0.568. The results of this study suggest that further optimization of the field triage guidelines is needed to identify high-risk TBI and TSI patients.