Background: The intestinal villi's tip, which is frequently wounded in necrotizing enterocolitis (NEC), contains cells that contain intestinal fatty acid binding protein (I-FABP). In this study, we looked at the use of serum I-FABP in predicting the severity and early diagnosis of NEC. Early signs of NEC, such as abdominal distension, bloody stools, or gastric retention, are sometimes vague. Intestinal coagulate or ischemia necrosis that begins at the mucosa and spreads into the submucosa and muscularis externa are histological characteristics of NEC. Objectives: To assess the amount of intestinal fatty acid binding protein in the blood as a possible biomarker for early diagnosis and prognosis in preterm neonates with necrotizing enterocolitis. Patients and methods: This is a prospective cohort study conducted on 40 pre-term neonates of both sexes in NICU at Menoufia University Hospital, during the period from March 2019 till April 2022. Results: Capillary refilling time was significantly prolonged, while RR and HR were lower in patients than in controls. Hb, PLT counts and serum levels of Na, K and Ca were significantly lowered among patients than controls.C-reactive protein was significantly increased among patients' group (4.45 ± 1.01) than controls group (1.35 ± 0.32), (P= 0.001). Also, 16 (80%) in patients with NEC had no growth in blood culture with a significant difference (P= 0.035) and mean serum intestinal fatty acid binding protein level was significantly higher at diagnosis in patients group (73.3 ± 11.1) than in control group (4.87 ± 1.11),(P= 0.001). ROC curve analysis showed that cutoff point of serum intestinal fatty acid binding protein in diagnosis of preterm neonates with necrotizing enterocolitis was 7.75 ng/ml with sensitivity of 100%, and specificity of 100% at AUC of 1.00 and bell stage in necrotizing enterocolitis was 72.5 ng/ml with sensitivity of 86%, and specificity of 100% at AUC of 1.00. Conclusion:According to the clinical presentation of NEC, serum I-FABP levels were higher in preterm neonates with NEC compared to age-sex matched controls. Serum I-FABP levels were also higher according to the severity of NEC. Serial assessments of serum I-FABP levels might therefore be a helpful indicator of NEC prognosis. Serum I-FABP can therefore be a reliable serologic biomarker for the early diagnosis, prognosis, and assessment of the severity of NEC in preterm neonates.