OBJECTIVES:: To evaluate the use of gut barrier proteins, liver-fatty acid binding protein (L-FABP), intestinal-fatty acid binding protein (I-FABP), and trefoil factor 3 (TFF3), as biomarkers for differentiating necrotizing enterocolitis (NEC) from septicemic/control infants and to identify the most severely affected surgical NEC from nonsurgical NEC infants. BACKGROUND:: Clinical features and routine radiologic investigations have low diagnostic utilities in identifying surgical NEC patients. METHODS:: The diagnostic utilities of individual biomarkers and the combination of biomarkers, the LIT score, were assessed among the NEC (n = 20), septicemia (n = 40), and control groups (n = 40) in a case-control study for the identification of proven NEC and surgical NEC infants. RESULTS:: Plasma concentrations of all gut barrier biomarkers and the LIT score were significantly higher in the NEC than in the septicemia or control group (P < 0.01). Using median values of biomarkers and the LIT score in the NEC group as cutoff values for identifying NEC from septicemic/control cases, all had specificities of 95% or more and sensitivities of 50%. Significantly higher levels of biomarkers and the LIT score were found in infants with surgical NEC than in nonsurgical NEC cases (P ≤ 0.02). The median LIT score of 4.5 identified surgical NEC cases with sensitivity and specificity of 83% and 100%%, respectively. A high LIT score of 6 identified nonsurvivors of NEC with sensitivity and specificity of 78% and 91%, respectively. CONCLUSIONS:: The LIT score can effectively differentiate surgical NEC from nonsurgical NEC infants and nonsurvivors of NEC from survivors at the onset of clinical presentation. Frontline neonatologists and surgeons may, therefore, target NEC infants who are most in need of close monitoring and those who may benefit from early surgical intervention. © 2013 Lippincott Williams and Wilkins.